Cleaner Production
Cleaner Production in the Queensland
Foundry Industry
Project Summary
Key Findings
鈥? This project was initiated by the Queensland EPA, Sustainable Industries
Division in conjunction with the Australian Industries Group. These two
groups co-developed the draft Environmental Guideline, Beneficial re-use
of ferrous foundry by-products.
鈥? The project was facilitated by the UNEP Working Group for Cleaner
Production based at the University of Queensland. It aimed to build on the
beneficial reuse project to identify opportunities to reduce waste and
increase efficiency at source.
鈥? A detailed Manual and Self Assessment Guide has been developed to
provide a detailed list of ideas that foundries may by able to apply to their
own processes. It also provides step-by-step methodology to undertaking a
Cleaner Production Assessment and developing a Cleaner Production Plan
for foundry operations.
鈥? While foundries already undertake Cleaner Production to some extent,
most foundries have significant opportunities to achieve further
improvements in these areas. By keeping an open mind, thinking laterally
and focusing on continuous improvement, the ideas developed in this
project can help improve the competitiveness of the Queensland foundry
industry
鈥? The project also included a series of site visits and demonstration projects
as well as workshop based training for industry and government. Over
twenty of the foundries in Queensland have been involved in these
activities.
October 1999
UNEP Working Group for
Cleaner Production
Page 1 Page 2
Background
In March 1999, the EPA and the Foundry Industry Environmental Working Group released its
draft Environmental Guideline, Beneficial re-use of ferrous foundry by-products. This project
was designed to help facilitate the increased practice of beneficial reuse in the industry. This
has already helped to reduce the quantity of foundry waste that is sent to landfill and is
reducing the cost to industry for disposing of this material. It will also lead to flow on benefits
by providing inexpensive inputs to other industries. The foundry sector generates over 50,000
tonnes of foundry by-products, predominantly sand, each year. Around 85% of this material
is currently sent to landfill. Beneficial reuse could be increase to around 70% over the next
five years. This would reduce the quantity of material going to landfill by 25,000 tpa with a
potential saving of $500,000 pa.
The industry has realised that, beyond the potential benefits of beneficial reuse, there is a
significant opportunity to reduce waste and improve resource efficiency at source. These
practices can reduce waste disposal costs but also offer benefits such as reduced
purchasing costs, improved casting quality, increased productivity from improved work
conditions.
The UNEP Working Group for Cleaner Production, based at the University of Queensland
has expertise in helping companies and industry groups identify opportunities in these areas.
The group has recently completed a successful project with the Queensland metal finishing
industry, which used a similar methodology to the foundry project.
Project Summary
The major steps in the project can be seen in the following diagram:
Development of
Consultation with industry
Literature / Internet search Self Assessment Guide
Site visits to discuss project
Monitoring
Demonstration Projects
success
Finalisation of
Training Workbook
Information Workshops
Phase One: Self Assessment Guide
A literature review and industry consultation was undertaken to investigate the status of
Cleaner Production techniques locally, nationally and internationally.
A Self Assessment Guide was developed to provide a step-by-step guide to Cleaner
Production as well as checklists that provide Cleaner Production options for the foundry
industry.
The Guide was launched as part of detailed Cleaner Production manual at a workshop based
training program in October 1999. This program was attended by fifteen Queensland
foundries as well as government representatives and consultants.
Page 3
Phase Two: Site Visits and Industry Consultation
Fourteen casting operations were visited in June and July 1999. Collectively, these
companies account for around 90% of the waste generated by the industry. Many
companies were keen to receive assistance in developing Cleaner Production programs and
were particularly interested in being made aware of the options that are available to them.
The current Status of Cleaner Production in the Queensland foundry industry is discussed
further below.
Phase Three: Demonstration Projects
Several companies expressed an interest in participating in the project further to look at some
specific Cleaner Production issues. Three minor demonstration projects were carried out at
these sites to help advance some specific opportunities that were identified.
Phase Four: Training Workbooks and Information Sessions
A comprehensive reference manual was developed to support the Self Assessment Guide.
The sections in the manual include:
鈥? Part 1: Background.
鈥? Part 2: Cleaner Production Ideas.
鈥? Part 3: Case Studies.
鈥? Part 4: Self Assessment Guide.
鈥? Part 5: Overview of Foundry Processes.
鈥? Part 6: Cleaner Production Implementation Guide
鈥? Part 7: Resources
The ideas section is organised into the following sections.
鈥? Improving Housekeeping Practices.
Housekeeping is an important part of the Cleaner Production process and can help raise
staff awareness about environmental and efficiency issues as well as achieving
significant savings at minimal cost. Ideas include maintaining a tidy site, segregation of
by-products, inventory and maintenance practices.
鈥? Selecting Alternative Inputs.
The choice of inputs used in the foundry process can have a significant impact on costs
and environmental performance of the operation. Changing inputs can help to improve
the efficiency of the operation and can help 鈥榙esign out鈥? environmental and efficiency
problems from the process.
鈥? Improving Metal Yields.
Improving metal yields can save the company money in a range of areas - reducing the
energy needed to melt and remelt excess and reject metal. Topics include improving box
yields and gross casting weight through better methoding, precision and direct pouring
techniques, and the impact of casting simulation methods.
鈥? Improving Energy Efficiency.
Increasing energy efficiency presents a challenge for the industry. Case studies indicate
that most foundries could achieve significant energy savings by optomising current
practices. Other technologies may also help companies improve their efficiency. Topics
include efficient melting practices and technologies, recapturing waste heat, improving
the efficiency of ancillary services (e.g. compressed air, motors etc.), new demands for
energy (e.g. more baghouses, sand reclamation etc.)
鈥? Minimising Foundry By-products.
Minimising by-product use and waste has the potential to reduce the cost of purchasing
new inputs such as sand and binders, reducing unnecessary processing and reclamation
of sand and reducing the cost of handling and disposing of by-products. Topics include
how to improve the efficiency of sand and binder use in the foundry, reducing box
weights, and reclamation options.
鈥? Production Planning and Improvement.
Automation, computerisation and process control will play an increasing role in improving
process efficiency, minimising and managing resources and by-products and improving
product quality and customer service. Topics in this area include emerging technologies
such as rapid prototyping, CAD/CAM, casting simulation, integrated manufacturing
systems, the use of the internet in commerce.
Current Status of CP
The general awareness of Cleaner Production among the industry representatives was high.
This was particularly the case among the members of the Environmental Steering Committee
that was responsible for developing the EPA鈥檚 Beneficial re-use of ferrous foundry by-
products manual. All companies were able provide specific examples of Cleaner Production
activities that have been undertaken and many had developed plans for future
improvements. The smaller and non-ferrous foundries tended to have a lower interest in
exploring improvement opportunities for their operations as they perceived there were fewer
options, the quantities produces were too small to justify many options, non-ferrous sands
had restricted opportunities for reuse, and in some cases the value of production was
relatively high making the relative importance of waste reduction lower. Most of the interest
in Cleaner Production came from the larger foundries where the costs savings were seen to
be significant.
With the exception of noise and odour, the most significant aspect of foundry processes has
been the generation of large quantities of foundry byproducts and wastes. The companies
surveyed generated approximately 50,850 tonnes of foundry byproduct per annum.
Around 85% of this material is being sent to landfill. The remainder is being put to beneficial
reuse as night cover at landfills or as composting material. The total cost to industry to
dispose of this material is around $830,000.
If the companies achieve their stated goals, the quantity of material diverted from landfill
could be realistically increased from the current level of 15% to around 70% over the next five
years. This would reduce the quantities of material going to landfill by 25,000 tpa. The
potential savings for disposal of this material could be in the order of $500,000. This does
not include any costs incurred for handling the material.
Sand reclamation has even greater potential for the industry. This is due to the dual benefits
of reducing disposal costs and the reduced cost of purchasing new sand. Internal recycling
currently averages around 39%. This already saves the industry a significant amount of
money and helps minimise material entering landfill. Current plans, being considered by the
industry, may increase the average level of internal recycling of sand to over 50%. This would
save the industry a further $172,000 in disposal costs and over $1 million in sand purchase
costs.
Energy efficiency is an area where most foundries recognize there is opportunity for
improvement. All but one of the foundries visited use electric furnaces, either electric arc or
electric induction. Many of these systems have been installed in the past five years in an
effort to improve energy efficiency, environmental performance and increased throughput.
Energy, however, remains one of the most important issues facing the industry.
The major Cleaner Production plans that are being considered by the industry include:
鈥? Beneficial reuse of industry byproducts, particularly sand, baghouse dust and shotblast.
鈥? On-site and off-site sand reclamation and reuse.
鈥? Simple energy efficiency programs (eg. covering ladles, energy management and
production scheduling, ensuring equipment is turned off when not in use, etc.).
鈥? More complex energy efficiency programs (e.g. capturing waste heat from the furnaces
and heat treatment processes for generation of electricity, acrylic paint drying, wet sand
reclamation systems, etc.).
鈥? Increase on-site recovery and reuse of metals including shotblast, machining fines and
baghouse dust metals.
鈥? Better segregation of shotblast from sand to increase reclamation.
鈥? Conversion of baghouse dust to slag to reduce disposal costs or increase beneficial
reuse options.
鈥? Regenerating machine cutting oils.
鈥? Investigation of new resin systems.
鈥? Changing energy sources (e.g. grid power to bagasse, propane to natural gas, diesel to
electricity).
鈥? Improving layout and housekeeping practices.
This is not an exhaustive list of options for the companies surveyed but represents the
options that are currently being explored and have the potential to be implemented in the
short to medium term.
The Next Steps
An industry workshop was held on Monday, 11th October at the Queensland Manufacturers
Institute to discuss Cleaner Production opportunities in the foundry industry. The session
was hosted by the Queensland Environmental Protection Agency (EPA) and the Australian
Industry Group (AIG), chaired by Mr. Phillip Glew and presented by staff of the UNEP
Working Group for Cleaner Production. In attendance were 17 representatives from 15
foundries in South East Queensland, 3 AIG representatives, 1 representative from the EPA
and 3 representatives from the UNEP Working Group.
During the workshop, participants were asked to identify what they believe are the key
Cleaner Production opportunities for the foundry industry and the role of individual foundries,
industry groups and government agencies in implementing these opportunities. The specific
areas covered were sand by-products, other by-products, metal yields and energy yields.
The recommendations generated by the Queensland industry are summarised below:
鈥? Metal yield and energy represented the most significant untapped opportunity for most
foundries.
鈥? Most foundries have already made significant gains in the area of waste minimisation and
by-product reuse but there is still scope for further improvement in many foundries. Most
of the large foundries are actively pursuing beneficial reuse strategies.
鈥? At the foundry level, progress in Cleaner Production required commitment in the following
areas.
鈾? Ensure the top management team is driving the project;
鈾? Appoint a champion who can overcome the inevitable obstacles;
鈾? Develop effective monitoring, and performance indicators for key resorces, by-
products and environmental outcomes;
鈾? Develop effective incentive programs to encourage staff participation and to share the
rewards gained from the improvement process;
鈾? Undertake awareness and skills training;
Page 5
鈾? Be open to cross-fertilisation of ideas within the industry;
鈾? Encourage suppliers of binders and other inputs to develop less toxic and more
reactive products;
鈾? Encourage greater communication between designers, engineers and foundrymen at
the design stage to reduce over-engineering and improve operational efficiency; and
鈾? Participate in educational activities that increase the community鈥檚 awareness of the
foundry鈥檚 technical capabilities (eg. foundry tours for school groups).
鈥? At the industry level, the following roles were identified for the industry group:
鈾? Facilitate increased interaction between foundries to advance mutual Cleaner
Production goals;
鈾? Coordinate the development of a chain management approach to work with key
suppliers and customers. For example, investigate the viability of a centralised sand
reclamation facility or develop a project with major customers to improve awareness of
the role of good design in efficient manufacturing;
鈾? Actively market beneficial reuse options;
鈾? Actively promote the industry as an innovative, environmentally conscious and
sophisticated sector to overcome its dirty and low-tech image; and
鈾? Increase the industry group鈥檚 role as a clearinghouse for Cleaner Production,
environmental and technical information.
鈥? At the government level, the following roles were identified:
鈾? Work with industry to build on the emerging non-regulatory, partnerships models for
environmental protection and improvement;
鈾? Continue to break down barriers for beneficial reuse including the development of
markets, the amendment of government specifications to allow reuse, and increasing
the confidence of and benefits to the private sector to undertake reuse;
鈾? Provide financial assistance for industry wide research activities particularly in the
areas of sand reclamation for small foundries, shared reclamation facilities, energy
efficiency and metal yield; and
鈾? Build on the Cleaner Production project to develop site specific skills based training of
staff.
Conclusion
In general, the outlook for Cleaner Production in the industry is very promising. Both
beneficial reuse and internal reclamation are likely to significantly improve environmental
performance and reduce costs to the industry over the next five years. However, there is still
work to be done to remove some barriers. These include :
1) removing legislative and bureaucratic costs of beneficial reuse and environmental
compliance;
2) increasing opportunities for the foundries to work together to develop solutions for mutual
problems where individual companies are too small to work alone;
3) adopting a supply chain management approach particularly in terms of working with major
suppliers to develop better inputs and developing centralised recycling facilities;
4) working to enhance the image of the foundry industry as an innovative, environmentally
conscious and high-tech industry.
Report Prepared By:
This report was prepared for the Queensland Environmental Protection Agency by the
UNEP Centre for Cleaner Production and the CRC for Waste Minimisation and Pollution
Control which are based at the University of Queensland. The research team included
Stuart Pullar, Bob Pagan, Marguerite Lake and Bill Clark.
The foundries involved in the projects were:
ANI Bradkin - Ipswich Foundry
ANI Bradkin - Runcorn Foundry
Associated Engineering
Austcast Foundry
Bundaberg Foundry
Bundaberg Metal Industries
Crevet Ltd
Crown Castings
Downs Aluminium Castings
Farnell & Thomas
Investment Casting QLD
Larges Foundry
Mallets Foundry
Nu-Spray Foundry
Qalcast Foundry, Gold Coast
Reliance Manufacturing Company
Toowoomba Foundry
TYCO - Gold Coast Foundry
Walkers Foundry, Maryborough
WareTech Foundry
The UNEP Centre can be contacted at:
Bob Pagan
The UNEP Working Group Centre for Cleaner Production
Environmental Management Centre
Chamberlain Building
The University of Queensland
BRISBANE QLD 4072
Ph: (07) 3365 1545
Fx: (07) 3365 6083
Cleaner Production Manual for the Queensland Foundry Industry November 1999
FOREWORD
In early 1998, on-going correspondence between the then Department of
Environment and various foundry operators sought to clarify how waste sand
should be considered under the schedule of regulated wastes. Many foundry
operators were exploring potential beneficial re-use options such as
composting and concrete manufacture, but the uncertainty of how the
Department might consider the re-use options often caused negotiations to
break down.
To deal with these barriers, a working group was formed consisting of
representatives from a number of foundries as members of the Australian
Industry Group, and staff of the Environmental Protection Agency (EPA). This
group successfully produced a guideline entitled 鈥淓nvironmental Guideline -
Beneficial re-use of ferrous foundry by-products - draft guideline鈥?. This
guideline set out an extensive range of beneficial re-use options for each of the
primary foundry by-products and set those conditions under which the EPA
would be satisfied that no environmental harm would ensue. This successfully
waylaid any fears of third party users who might seek EPA endorsement.
With the encouraging partnership that had already been formed with the
Australian Industry Group and its members, it was considered appropriate for
the working group to continue collaboration in the preparation of this Cleaner
Production Manual for the Casting Industry. This was a logical next step from
the end-of-pipe focus of the guideline to addressing process and waste
reduction within the industry.
At the time, the EPA had just been formed. Further, within the EPA, the
Sustainable Industries Division seeks to inform industry that businesses have
the potential to improve environmental performance AND to increase profits.
Eco-efficiency and Cleaner Production offer the means by which even minor
changes in a business can realise substantial financial rewards, reduced
wastes and promote effective marketing and competitive advantages.
The Sustainable Industries Division is a solutions-driven EPA initiative
assisting Queensland industry achieve higher levels of environmental
performance while boosting profitability and competitiveness. It has been
realised by the new Division that the Australian Industry Group and other
industry associations also seek to boost business profitability and
competitiveness. It is the desire of the Sustainable Industries Division to
develop partnerships to work more closely with these important industry
assistance bodies.
The EPA, in partnership can assist business identify mutually beneficial
solutions. This Cleaner Production Manual is an example of the benefits of
working in partnership with industry and promises to realise considerable
profits for industry in the adoption of cleaner production options. Through
partnership arrangements, business assistance programs and information
facilities, the Sustainable Industries Division will help industry better integrate
business and environmental decision making in the achievement of eco-
efficiency, innovation and business growth.
Cleaner Production Manual for the Queensland Foundry Industry November 1999
This manual forms a part of the program to accelerate the achievement of
sustainable development across the State.
This manual provides information about Cleaner Production opportunities
within the foundry industry, to point the way towards greater profitability and
improved environmental performance. It focuses on those aspects which are
most achievable in the short and medium term, and which require limited or no
capital expenditure. It has been developed with small business in mind, as it is
recognised that small business is unable to self-fund research and develop
training programs.
The development of Cleaner Production requires an open-minded approach by
industry and government to explore improvement options and overcome the
inevitable barriers that must be faced. We encourage the industry to consider
the ideas presented in this manual and actively evaluate relevant options that
will make the Queensland foundry industry more competitive and sustainable.
This manual has been prepared by:
The UNEP Working Group Centre for Cleaner Production
Bob Pagan, Stuart Pullar and Marguerite Lake
Technology Management Centre, University of Queensland
Tel: (07) 3365 1545, Fax: (07) 3365 6083
email: r.pagan@mailbox.uq.edu.au
web site: http://www.geosp.uq.edu.au/emc/CP/
On behalf of:
The Queensland Environmental Protection Agency
Mr Ken McKeon
Tel: (07) 3227 8925
And:
Cleaner Production Project Steering Group
Mr Phil Glew, RMC
3252 3646
The authors would also like to thank all the foundries that were involved
foundry site visits, Cleaner Production assessments, demonstration projects,
steering meetings and workshops. This assistance was valuable in preparing
this manual.
ANI Bradkin - Ipswich Foundry Investment Casting QLD
ANI Bradkin - Runcorn Foundry Larges Foundry
Associated Engineering Mallets Foundry
Austcast Foundry Nu-Spray Foundry
Bundaberg Foundry Qalcast Foundry, Gold Coast
Bundaberg Metal Industries Reliance Manufacturing Company
Crevet Ltd Toowoomba Foundry
Crown Castings TYCO - Gold Coast Foundry
Downs Aluminium Castings Walkers Foundry, Maryborough
Farnell & Thomas WareTech Foundry
Cleaner Production Manual for the Queensland Foundry Industry November 1999
Table of Contents
Part 1: Background
Part 2: Cleaner Production Ideas
Part 3: Cleaner Production Case Studies
Part 4: Self Assessment Guide
Part 5: Overview of Foundry Processes
Part 6: Cleaner Production Implementation Guideline
Part 7: Resources
Cleaner Production Manual for the Queensland Foundry Industry November 1999
PART 1: BACKGROUND
1. Foundry Industry in Queensland
The casting of metal in foundries has been undertaken for thousands of years
and is one of the oldest and largest recycling industries in the world. Virtually
all scrap metal collected for recycling goes to foundries to make new products,
in particular scrap metal from the automobile and heavy industries. For
Australia as a whole, the foundry industry is a large and important part of the
countries industrial base.
About 40 of Australia鈥檚 200 foundries are located in Queensland. The
Queensland foundry industry produces 44000 tonnes of castings annually,
which is one-third of the national total and more than a quarter of this is
supplied to the export market. The industry in Queensland employs more than
1100 people (EPA, 1999).
Foundry operations in Queensland range from very small operations producing
high quality castings in jobbing operation to companies employing more than
400 people and producing products such as agricultural and mining equipment,
construction components, railway rolling stock and pipework fitting on a large
scale. Fourteen foundries were visited as part of this project. Table 1 provides
a listing of these foundries including an indication of the types of products they
produce and their scale of operation. These companies account for about 90%
of foundry production in the State. There are an additional 20-30 small
foundries in the state, predominantly ferrous and non-ferrous jobbing shops
that serve local markets.
The industry can be divided into two sectors; ferrous and non-ferrous. Ferrous
foundries cast iron and steel products while non-ferrous foundries cast a
variety of other metals such as aluminium, copper, zinc, lead, tin and nickel.
More than 75% of products by volume is ferrous. Although non-ferrous
industries use the same basic moulding and casting techniques, by-products
can be different from those produced from ferrous industries (EPA, 1999).
The majority of foundries in Queensland use modern electric furnaces, either
electric arc or electric induction. Many of the electric furnaces in operation have
been installed in the past five years in an effort to improve energy efficiency,
environmental performance and increased throughput.
A flat or declining domestic market and significant competition from overseas
foundries over the past two decades has placed pressure on the profitability
Australia鈥檚 foundry industry. This has led to significant restructuring in the
industry. The number of foundries has decreased with those companies still in
operation being the larger, more competitive, export oriented foundries or those
with more diversified operations. As a result, the industry has tended to take a
cautious approach to capital investment which has weakened international
competitiveness and limited local research and development (CoA, 1985).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Table 1: Major foundries in Queensland
Metal cast Major products Capacity
ANI Bradkin - Ipswich Ferrous Large industrial castings. Medium
Foundry
ANI Bradkin - Runcorn Ferrous Large castings for the Large
Foundry mining, transport and
other industry
Austcast Foundry Ferrous Small to medium sized Medium-
steel and iron castings. Large
Bundaberg Foundry Iron / steel & Agricultural, milling and Medium-
some brass and mining equipment, Large
bronze pumps, gears and gear
casings
Bundaberg Metal Industries Ferrous Predominantly pipes and Small
fittings.
Investment Casting QLD Ferrous, non- Precision engineering Small
ferrous, specialty components, feature
alloys. castings and artwork.
Nu-Spray Foundry Non-ferrous Small volume, high Small
(aluminum & quality castings
some gunmetal,
brass & bronze)
Qalcast Foundry, Gold Non-ferrous Small volume, high Small
Coast (bronze, quality castings
aluminium)
Reliance Manufacturing Non-ferrous Water meters and Medium
Company (gunmetal) specialty valves
Toowoomba Foundry Ferrous Agricultural, mining, & Medium-
transport equipment & Large
building components
TYCO - Gold Coast Ferrous Pipeline valves & fittings Medium-
Foundry Large
WareTech Ferrous Specialty Engineering Medium
products
Walkers Foundry, Ferrous Railway rolling stock, Large
Maryborough sugar milling equipment
and general industrial
castings.
Large: >10000 tonnes per year;
Key
Medium: > 2000 tonnes per year;
Small: < 2000 tonnes per year.
Page 2
Cleaner Production Manual for the Queensland Foundry Industry November 1999
2. By-product Management Issues for the
Industry
Although the foundry industry is traditionally been viewed as dirty and
hazardous, modern foundry processes are relatively clean and impacts are
generally related to environmental nuisance issues such as noise and odour
rather than impacts that are hazardous to human health and the environment.
Most foundries have made considerable effort to minimise these impacts and
foundries located in build up areas, have developed sophisticated noise and
odour management systems and regularly monitor emissions from the site.
The most significant waste management issues for the foundry industry is the
generation of large quantities of spent sand and other solid by-products such
as baghouse dust and slag. Table 2 provides quantities of sand and other solid
wastes generated by the foundry industry in Queensland. Historically, many
foundries disposed of these materials on site, however this practice has given
way to landfill disposal. As the costs of landfill disposal continue to rise,
alternatives to disposal are being pursued.
These waste and by-product streams are relatively benign, particularly those
generated from ferrous foundries. Most chemical additives used for sand
binding are inert or of organic origin which biodegrade relatively quickly
(EPA,1999). For ferrous foundries, waste sand typically passes toxic
characteristic leaching procedure (TCLP) tests and can therefore be sent to
non-secured landfill. Non-ferrous foundry sands are usually sent to secured
landfill due to the presence of heavy metals. Baghouse dust from ferrous
foundries is also sent to secured landfill, due to the fact that the dust is
extremely light so is a potential occupational health and safety issue.
In total, about 46000 tonnes of spent foundry sand is generated per year in
Queensland, 85% of which is disposed to landfill. Around 4,920 tonnes is being
used as night cover at landfill sites and a further 2,280 tonnes is being used as
a composting material. Therefore around 15% of the total spent sand is
currently being used for some form of beneficial reuse.
In response to the increasing costs of landfill disposal, beneficial reuse of
foundry byproducts has received considerable attention by the industry in
recent years, culminating in the development by the Queensland EPA of an
Environmental Guideline, Beneficial re-use of ferrous foundry by-products. Five
of the major ferrous foundries in Queensland hope to achieve 100% beneficial
reuse for their major waste streams, (i.e. sand, baghouse dust and slag) within
the next five years. If these companies achieve their stated goals, the volume
of material diverted from landfill could be realistically increased from the current
level of 15% to around 70% over the next five years. This would reduce the
volume of material going to landfill by 25,000 tonnes per year. Beneficial reuse
options are generally more limited for non-ferrous foundries, small foundries,
and foundries that are located a long way from potential users of the by-
products.
Page 3
Cleaner Production Manual for the Queensland Foundry Industry November 1999
Table 2: Quantities of sand and other solid wastes
generated by Queensland foundries
Waste Tonnes/year
Spent green sand 11,322
Spent phenolic bonded sand 9,799
Spent silicate bonded sand 17,688
Spent furan-bonded sand 3,496
Resin coated sand 3,913
Spent silicate bonded zircon 8
Core sand 1,140
Baghouse dust (FFDC Dust) 3,023
Shot-blast dust 616
Furnace slag 2,465
Dross 127
Induction furnace lining 114
standard firebrick 8
ladle lining 807
Furnace consumables - thermocouples etc. 48
Sand reclamation dust 132
Shot blast sand 72
Clay graphite used pots (borden) 1
General waste which cannot be recycled 1
Approximate Total 54,780
Note: This table does not include the Maryborough and Bundaberg foundries. A survey
conducted in 1995 by the MITA (now the Australian Industries Group) estimated the State鈥檚
waste foundry sands (including these foundries) to be approximately 75,690 tonnes per year.
The economic downturn has reduced the volume of waste generated by the industry in
recent times.
Source: (EPA, 1999)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
While beneficial reuse will play an important role in by-product management,
greater potential value can be gained from Cleaner Production. Beneficial
reuse is an 鈥榚nd-of-pipe鈥? strategy that reduced the cost of waste once it has
been generated. Cleaner Production stops the waste occurring in the first place
so can potentially reduce the cost of purchasing materials as well as reducing
the cost of unnecessary processing, handling and disposal costs.
In general, the outlook for Cleaner Production in Queensland鈥檚 foundry industry
is quite promising with many of the ideas presented in this manual already
being undertaken. Based on a recent survey of Queensand鈥檚 major foundries,
companies have actively sought to minimise waste and maximise resource
efficiency in a number of areas throughout the foundry. Some of the most
interesting examples include:
鈥? Beneficial reuse of industry byproducts, particularly sand, baghouse dust
and shotblast;
鈥? On-site and off-site sand reclamation and reuse;
鈥? Energy efficiency programs (eg. covering ladles, energy management and
production scheduling, ensuring equipment is turned off when not in use,
capturing waste heat from the furnaces and heat treatment processes);
鈥? Increasing on-site recovery and reuse of metals including shotblast,
machining fines and baghouse dust metals;
鈥? Better segregation of shotblast from sand to increase reclamation;
鈥? Conversion of baghouse dust to slag to reduce disposal costs or increase
beneficial reuse options;
鈥? Regenerating machine cutting oils;
鈥? Investigation of new resin systems;
鈥? Changing energy sources (e.g. grid power to bagasse, propane to natural
gas, diesel to electricity); and
鈥? Improving layout and housekeeping practices.
Reclaiming sand for reuse within the foundry process is seen as an important
means of reducing the amount of sand disposed to landfill. Many of the larger
foundries currently undertake manual sand reclamation. For foundries that
produce large, iron castings sand recovery rates for manual reclamation can be
as high as 90-96%, however for most operations in Queensland, recovery rates
for those foundries undertaking reclamation is typically around 70-80%.
A number of Queensland companies are in the process of installing manual
sand reclamation systems or optimising the systems to increase recovery rates.
Thermal reclamation has not been widely adopted in Queensland due to the
high cost of the systems and the relatively small volumes of sand generated in
the state. One Queensland foundry, using a shell casting process, has recently
commenced thermal sand reclamation to recover 100% of its waste sand. Many
of the conventional sand casting operations have investigated thermal
reclamation and may invest in these systems in the future.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Figure 1: Sand Flows in the Queensland Foundry
Industry
The Queensland Foundry Industry
Total Sand Used
New Sand Purchased Spent Sand
177,000 tpa
48,700 tpa 46,400 tpa
Av. Recycle
36%
Landfill 85%
Beneficial Reuse 15%
Sand Lost
(< 5% baghouse dust
& general loss)
2,300 tpa
As depicted in Figure 1, the average rate of internal sand reclamation for the
Queensland foundry industry as a whole is currently 36%. Based on stated
plans by several Queensland foundries, the industry average could potentially
increase to 50% within the next two years.
Moving beyond 50% recovery will be relatively difficult. A further 5% may be
gained if companies improve the efficiency of the current systems. Further
gains will probably only be possible through the greater use of thermal
reclamation, by improving moulding techniques to reduce the sand input, by
changing to different casting processes or by identifying cost effective methods
for sand reclamation at small foundries.
While significant work has already been undertake, most Queensland foundries
recognise that there are many opportunities for continuous improvement in
terms of by-product minimisation and for improving resource efficiency. Key
areas identified by the sector include improved sand reclamation, metal yields,
energy efficiency and the beneficial reuse of byproducts. All of these
opportunities are discussed in further detail in this report.
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3. What is Cleaner Production & what are its
Benefits?
Cleaner Production focuses on eliminating waste and inefficiency at their
source, rather than finding 鈥榚nd-of-pipe鈥? solutions once the wastes have been
generated. It involves rethinking conventional methods to achieve 鈥榮marter鈥?
production processes and products to achieve sustainable production.
In adopting the Cleaner Production approach, try to consider how wastes can
be avoided in the first place rather than focusing on how to manage or treat
them once they have been generated.
Waste avoidance and reduction should be considered as the first options.
Once all avoidance and reduction options have been eliminated, then options
for on-site reuse and recycling can be considered. Only as a last resort should
treatment and disposal options be considered. This approach is depicted in the
Cleaner Production Hierarchy shown in Figure 2.
Cleaner Production has been the major environmental initiative for industries in
the 1990鈥檚. Thousands of manufacturing companies, including foundries have
taken up Cleaner Production approaches to manufacturing.
Figure 2: The Cleaner Production Hierarchy
Focus Strategy
Waste
Eliminate
Prevention
Reduce
Waste
Reuse
Management
Recycle
Treat & Control and
Dispose Disposal
Impact of
All media
Products
Air, Water, Solid
Work
Raw Materials
Energy
Procedures
Use
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
3.1 Saving money
Cleaner Production can save money; money which would have otherwise been
spent on wasted resources, waste treatment, disposal and compliance costs.
Cleaner Production strategies typically cost less than treatment and disposal
(so called 鈥榚nd-of-pipe鈥?) technologies. Complying with the emission limits
established by government through on-site treatment can be a significant cost;
may require specialist knowledge and attention, and generally provide no profit
for the organisation.
Many strategies, such as general housekeeping and process improvements
can be implemented at low cost and can have immediate benefits, up to 30% in
some cases. Substantial process modifications or technology changes will
require capital investment, however numerous case studies demonstrate that
pay-back periods can be as little as months to 2 years.
3.2 Preventing pollution
Pollution prevention by reducing energy, water and resource consumption and
minimising waste is at the core of Cleaner Production. With the emphasis on
reducing waste at the source rather than controlling pollution after it has been
generated with 鈥榚nd-of-the-pipe鈥? solutions, many pollution problems can be
eliminated.
3.3 Complying with environmental legislation
Working toward Cleaner Production will greatly assist in complying with stricter
environmental legislation, bringing the benefits of reduced liability, reduced
regulation, reduced monitoring costs, potentially reduced licensing charges and
better control over your business. Environmental regulations and standards are
becoming tighter and more comprehensive and this trend is expected to
continue in the future.
The Environmental Protection (Waste Management) Policy embraces the waste
management hierarchy and in some cases requires businesses to prepare a
Cleaner Production Plan. Table 3 contains the type of information that must be
included in Cleaner Production Plans.
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Table 3: Contents of a Cleaner Production Plan
A Cleaner Production Plan must A Cleaner Production Plan may
contain details of: need to address other issues such
as:
鈥? Current waste management 鈥? input substitution鈥攔eplacing an
practices; input with a non-hazardous or less
hazardous substance; and/or
鈥? Material, energy and resource
鈥? product reformulation鈥?
inputs;
substituting an alternative end
鈥? Material, waste and energy outputs;
product which is non-hazardous
鈥? Impacts of the production process or less hazardous upon use,
release or disposal; and/or
on environmental values;
鈥? production process modification鈥?
鈥? Opportunities and actions to be
upgrading or replacing existing
taken to avoid and reduce waste
production process equipment
(including toxicity, energy and
and methods with other
water);
equipment and methods, and/or
鈥? Opportunities and actions to be
鈥? improved operation and
taken to recycle wastes;
maintenance of production
鈥? Recommendations of any life cycle
process equipment and
assessment conducted;
methods鈥攎odifying or adding to
鈥? Targets and goals; existing equipment or methods;
and/or
鈥? Program of action and timeframes;
鈥? closed-loop recycling鈥攔ecycling
鈥? Any certified or approved quality or extended use of substances
assurance or environmental which become an integral part of
management system or standard; the production process.
鈥? Monitoring and reporting program.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
PART 2: CLEANER PRODUCTION IDEAS
Introduction......................................................................................................... 5
1. Improving Housekeeping Practices ............................................................. 7
1.1 Workshop Tidiness .................................................................................. 8
1.2 Preventive Maintenance .......................................................................... 9
1.2.1 Compressed Air ................................................................................ 9
1.2.2 Natural Gas..................................................................................... 10
1.2.3 Water .............................................................................................. 11
1.3 Inventory Control ................................................................................... 12
1.4 Staff Training ......................................................................................... 13
2. Selecting Alternative Inputs....................................................................... 15
2.1 Alternative Mould Coatings.................................................................... 16
2.1.1 Water-based systems ..................................................................... 16
2.2 Water-based Shell for Investment Casting ............................................ 19
2.3 Improved Pattern Materials.................................................................... 19
2.4 Improved Riser Materials ....................................................................... 20
2.5 Alternative Energy Sources ................................................................... 20
3. Improving Metal Yields .............................................................................. 21
3.1.1 Minimising Melting Losses.............................................................. 25
3.1.2 Minimising Spilt and Pigged Metal.................................................. 25
3.1.3 Minimising the Weight of Castings ................................................. 27
3.1.4 Minimising Grinding Losses............................................................ 28
3.1.5 Minimising Scrap ............................................................................ 32
3.1.6 Casting Simulation.......................................................................... 32
3.1.7 Metal Filtering ................................................................................. 34
3.1.8 Direct Pouring Techniques ............................................................. 35
4. Improving Energy Efficiency ...................................................................... 37
4.1.1 Energy Auditing and Monitoring ..................................................... 39
4.1.2 Improvement Opportunities............................................................. 41
5. Minimising Foundry By-Products............................................................... 48
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
5.1 Segregation ........................................................................................... 50
5.2 Beneficial Reuse.................................................................................... 52
5.3 Optimising Sand and Binder Use........................................................... 54
5.3.1 Minimising Sand Use ...................................................................... 54
5.3.2 Optimising Binder Use .................................................................... 55
5.3.3 Sand reclamation............................................................................ 58
5.4 Minimising Other By-Product Streams ................................................... 72
5.4.1 Optimising other Refractory Material .............................................. 72
5.4.2 Optimising Blast Media Use............................................................ 73
5.4.3 Minimising General Waste.............................................................. 73
5.4.4 Reusing Swarf and Baghouse Dust ................................................ 73
5.4.5 Minimising Investment Shell Slurry................................................. 75
6. Production Planning and Improvement ..................................................... 77
6.1 Process Layout and Design ................................................................... 78
6.2 Rapid Prototyping and Pattern Making .................................................. 80
6.3 Changing Casting Processes................................................................. 84
6.4 Communication Tools and Integrated Control Systems......................... 86
7. Conclusions............................................................................................... 91
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
List of Examples
Example 1: Cleaner Production Incentive Schemes.......................................... 8
Example 2: Improved Air Compressor Management ....................................... 10
Example 3: Reducing water consumption........................................................ 12
Example 4: Infrared Drying ............................................................................... 18
Example 5: Water-based Investment Shell...................................................... 19
Example 6: Metal Recovery from Slag............................................................. 25
Example 7: Precision Pouring.......................................................................... 26
Example 8: Reducing Casting Weight Using Simulation Technology ............. 28
Example 9: Rapid Grinding Systems Minimise Grinding Waste ...................... 29
Example 10: Eliminating Fettling from the Foundry Process ........................... 30
Example 11: Filtering Metal ............................................................................. 34
Example 12: Direct Pouring ............................................................................. 36
Example 13: Energy Monitoring....................................................................... 40
Example 14: Energy Savings from Electric Ladle Preheating ......................... 45
Example 15: Converting from Cupola to Electric Furnaces ............................. 46
Example 16: Self-segregating Shotblast Units ................................................. 50
Example 17: Segregation reduces the cost of general waste.......................... 51
Example 18: Achieving Segregation................................................................ 51
Example 19: Beneficial Reuse......................................................................... 52
Example 20: Computer-aided Sand Control Systems...................................... 55
Example 21: Reducing Binder Inputs .............................................................. 57
Example 22: Reducing Binder Inputs in Queensland ...................................... 58
Example 23: Sand Optimisation - A Hypothetical Case Study.......................... 59
Example 24: Mechanical Sand Reclamation .................................................... 67
Example 25: Internal Reuse of Foundry Sand.................................................. 68
Example 26: Overseas Examples of Thermal Reclamation Systems .............. 70
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 27: Thermal Reclamation Systems In Queensland........................... 71
Example 28: Reducing the cost of general waste disposal ............................. 73
Example 30: Reducing Baghouse Dust Waste................................................ 74
Example 31: Recovery of Foundry Dust .......................................................... 75
Example 29: Quality Control of Investment Shell Inputs.................................. 75
Example 32: Redesigning the Foundry Process.............................................. 78
Example 33: Redesigning the Foundry Process (A Queensland Story) ......... 79
Example 34: Production Simulation in Foundries ............................................ 80
Example 35: A Vision for 2010 鈥? Communication and Control Systems in
a State-of-the-art Foundry ......................................................... 86
Example 36: Signicast Corporation 鈥? Continuous Flow Manufacturing ......... 88
Example 37: Reducing Pattern Lead Time Through Integrated
Communication.......................................................................... 90
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Introduction
The ideas presented in this section have been chosen to demonstrate the wide
range of Cleaner Production opportunities that exist in all areas of foundry
operations. Cleaner Production is a way of bringing about operational
improvement.
Cleaner Production is a process-oriented approach to environmental
management. Rather than simply controlling the outcomes with end-of-pipe
solutions such as waste treatment, which address only the results of inefficient
and wasteful production processes, Cleaner Production encourages companies
to look at production of waste and determine the best management strategy for
each case.
Cleaner Production focuses on elimination or reduction
of waste at source as the first priority.
The idea that improved environmental performance and business profitability
are compatible is a powerful one, and it is changing the way business is done
around the world.
While it is by no means an exhaustive list, the purpose of this document is to
challenge industry and motivate practitioners to look for innovative ways to
improve their operations. All the ideas described in this section are taken from
demonstrated industry case studies. Although not every suggestion will be
applicable to all foundries, readers should be able to find a number of ideas
that are worth considering for their foundry. By reviewing all the concepts
discussed in this report and thinking laterally about how they may be applied to
the reader鈥檚 specific operation, it should be possible to identify ways of
improving environmental performance and reducing costs.
In low-margin businesses, even minor cost savings can have a significant
impact on business profitability. For example, if the company has a 10%
margin, saving $100 dollars is equivalent to increasing sales by $1,000.
While this section focuses on positive benefits that can be achieved from
Cleaner Production, it does not address the many real and imagined
impediments to achieving Cleaner Production. The authors appreciate that
production and resource constraints can act as major barriers to making
process improvements. Nevertheless, companies need to find innovative ways
to overcome these barriers if they are to ensure the future competitiveness of
their operations.
Cleaner Production should be viewed as a strategic approach to operational
improvement. While many of the ideas discussed could be implemented as
stand-alone projects, the best results will be obtained by following a long-term
strategic approach. This approach starts with an assessment of the operation
to identify the sources and actual costs of waste and inefficiency. From this, an
integrated strategy can be developed that increases the overall efficiency of the
operation rather than simply optimising one part. General Guidelines to
implementing a Cleaner Production project are provided in Part 7: Cleaner
Production Implementation Guidelines.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
The Cleaner Production ideas in this report have been grouped under the
following headings:
鈥? Improving Housekeeping Practices
鈥? Selecting Alternative Inputs
鈥? Improving Metal Yields
鈥? Improving Energy Efficiency
鈥? Minimising Foundry By-products
鈥? Production Planning and Improvement.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
1. Improving Housekeeping Practices
Key Points
Housekeeping refers to a range of activities that relate to keeping the
workplace tidy, materials flowing smoothly and equipment working at optimal
efficiency.
Good housekeeping depends on active staff participation and awareness.
Training programs and awareness training in this area can lead to
improvements throughout the entire operation and can help develop a
participatory work culture. Top management support is critical to developing a
Cleaner Production culture. Incentives and recognition of involvement can also
help to drive the program.
Companies are likely to get the best results from Cleaner Production when it is
an integral part of how the business is run, not something extra the company
does. If it is used to drive change in the operation, Cleaner Production can lead
to real improvements in operational costs and environmental performance
which leads to long term competitiveness of the company.
Some of the key questions to ask in relation to housekeeping include:
鈥? Is the state of general housekeeping affecting the flow of work or causing
spills?
鈥? Are materials and chemical supplies being stored appropriately to minimise
the risk of damage or waste?
鈥? Can just-in-time purchasing practices be implemented to reduce the cost of
inventory management and avoid waste from out-of-date materials (e.g.
resins, catalysts and paints)?
鈥? Can preventive maintenance be use to optimise the efficiency of major
equipment and ancillary systems (e.g. furnaces, natural gas leaks etc.)?
鈥? Can we improve staff training programs to increase awareness about
Cleaner Production or to provide skill that increase operator efficiency?
鈥? Can we provide incentives (financial and non-financial) to increase
participation in Cleaner Production?
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Housekeeping improvements represent the simplest way to reduce pollution,
often without significant capital expenditure. For many foundries, Cleaner
Production programs that foster housekeeping and general staff awareness
can help to minimise waste throughout the operation. Linked with safety and
quality programs, these systems can also improve the quality of the working
environment and reduce costs.
Housekeeping improvements can include general workshop tidiness,
preventive maintenance and inventory control as well as simple process
improvements. Improving housekeeping is highly dependent on the active
participation of the foundry staff. Therefore, awareness-raising exercises along
with effective incentive schemes can significantly increase and maintain the
commitment of staff. Example 1 is a local example of this. Incentive programs
can include the use of small prizes (e.g. casket tickets or vouchers). They can
also include non-financial rewards such as awards and other ways of
recognising achievements.
Example 1: Cleaner Production Incentive Schemes
Tyco Water, on Queensland鈥檚 Gold Coast, has developed a monitoring
and incentive program called an 鈥業mprovement Share鈥? program. This
program measures improvement in a range of areas including hours
labour per tonne of product, foundry waste, general waste, energy
efficiency, safety and general housekeeping. All goals are measurable
and can be improved by the staff. Improvements are measured on a
quarterly basis, compared to the average performance of the previous
year, and the staff are paid a bonus representing half the value of the
improvement. The company believes that this approach has helped them
become one of the best foundries in the world in terms of safety and
environmental performance. This program has directly benefited the
bottom line.
Source: Spokesperson from Tyco Water
1.1 Workshop Tidiness
An important aspect of good housekeeping involves keeping the workplace
clean and free of clutter. This can reduce the risk of accidents and damage to
stock and equipment. For example, keeping stock in a designated inventory
area can reduce the risk of its becoming accidentally damaged by forklifts. In
the case of hazardous products, this can prevent spills in non-bunded areas.
Keeping the workplace free of clutter can also help to maintain a smooth flow of
work, which can increase the efficiency of the operation. Planning where
materials are stored and used can make them easier to access when needed.
Wastes also can be more easily segregated. It can be a good idea for teams or
supervisors to routinely audit the general tidiness of the shop floor and to
consider opportunities to improve work flow.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
1.2 Preventive Maintenance
The efficiency of equipment depends largely on the effectiveness of the
maintenance program. Preventive maintenance is typically more cost effective
than reactive maintenance because it helps ensure that equipment is operating
efficiently and therefore not wasting resources. It can help prevent costly
production stoppages and avoid the need for emergency overtime. Preventive
maintenance systems are typically more expensive in terms of purchasing parts
and in servicing equipment more frequently. In a well-run system, however
these costs can be less than the benefits
Preventive maintenance can help minimise leaks, spills and other potential
losses of resources. A regular schedule for cleaning and maintenance, with
inspection logs to follow up on repairs, is a good management option. Systems
to encourage staff to identify and report maintenance problems are an
important aspect of this program.
Computer packages are available that help schedule maintenance activities for
tools, machines and other equipment. These systems typically provide
functions such as equipment inventory, repair parts inventory, vendor and
service contractor management, time in use and downtime analysis, and
maintenance costs tracking. These packages can help to control manufacturing
costs, reduce scrap and rework, and ensure on-time delivery.
1.2.1 Compressed Air
Leaks in pipes and equipment can add up to huge losses of resources.
Compressed air loss is a major concern in many foundries as it costs more than
water, electricity or steam. Therefore leaks in this area can add up to a major
expense. An example of the extent of compressed air loss from leaking pipes is
provided in Table 1.
Table 1: The Cost of Compressed Air loss from leaks
(100 Psi)
Air loss (m3/year)
Leak size (mm) Cost/day Cost/year
<1 27,494 $0.79 $289
1鈥?3 139,196 $4.00 $1,462
3-5 508,343 $14.62 $5,338
>5 1,347,200 $38.76 $14,146
Note: Annual figures assume the loss is constant throughout the year.
Electricity costs are calculated at $0.07/kW.h and 15kW.h/m3 of compressed air.
Source: SEDA (1999)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
AuditAir (1999), an energy efficiency group, estimate that losses as high as
20% to 40% of capacity are common in many operations. Many foundries report
that, excluding the melting operations, compressed air is the largest source of
energy wastage (FTJ, 1999i). To put it into perspective, a 6 mm leak in a
compressed air line, while relatively easy to ignore, is equivalent to 300 60-watt
light bulbs left on (SEDA, 1999). Example 2 describes the experience of one
company in reducing the cost of compressed air.
Ancillary services, such as motors and drives, compressed air, lighting and
boiler plant, are typically responsible for up to half of total energy consumption
in foundry operations (ETSU, 1995). These are key areas for maintenance and
inspection.
Example 2: Improved Air Compressor Management
An energy audit of a UK foundry identified several opportunities to
improve air compressor management. The company reduced the
operating pressure of the compressed air supply from 7 bar to 6.5 bar. A
control system, costing 拢7,000 (A$17,500) was installed to ensure a
consistent supply. The system was also programmed to operate at 5 bar
during scheduled breaks and to shut-off during predetermined non-
production times. This reduced power consumption by around 26 kW.h.
One of the major uses for compressed air was to 鈥榖low-off鈥? mould cavities
to ensure cast cleanliness. The air guns on each of the three lines were
reprogrammed to be effective for 10 seconds per mould. This change
resulted in a 19.4% saving in compressed air usage.
Source: The Foundryman (1998a)
1.2.2 Natural Gas
The efficiency of natural gas use in a foundry is typically about 20%. Natural
gas use efficiency can be improved by the following:
a) Distribution. Eliminate the leaks that may exist in the natural gas distribution
system.
b) Combustion. Ensure that all burners operate at the correct air-to-fuel ratio
across the complete range of firing rates.
c) Excess air. Eliminate air infiltration to the furnace and provide combustion
air through the burner such that excess air approaches 0%.
d) Radiation losses. Put covers of refractory or ceramic fibre blankets over all
surfaces that are at elevated temperatures and generate radiation losses,
such as molten metal in ladles and launders.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
e) Conduction losses. Minimise the heat flow between the hot surface of the
refractory and the cold surface, by inserting ceramic fibre or fibre-type
sleeves between the working refractory and the furnace wall.
f) Heat sink losses. Replace refractories of high density and high heat
content, such that significant thermal energy is not expended just to bring
the refractory up to working temperatures.
g) Waste heat. Potential uses of waste heat include: preheating combustion air
in foundry processes; heating of building make-up air; heating of foundry
building.
1.2.3 Water
Because it is often a relatively minor cost, water efficiency may be overlooked
in many foundries. The Environmental Technology Best Practice Program in
the UK reported that the cost of water waste in the sector averages around 1%
of annual turnover and that around half of this is relatively easily to avoid
(ETBPP, 1995c). Therefore, although it is not as important as other issues,
there may still be some benefits in improving water efficiency in the operation.
There are also many relatively low-cost options for reducing water loss that
may generate a cost benefit to the company (see Example 3).
Table 2 shows some typical rates of water loss for equipment used in
foundries. These figures, which do not include the cost of wastewater, indicated
that even small drips can add up over time.
Table 2: Typical rates of water loss.
Potential source Rate of loss Annual loss Annual cost
(litres/hour) (kL)
(water only @
80c/kL)
Dripping union or flange 0.5 4.7 $3.76
(1 drop/second)
Leaking valve 6 53 $42.40
Leaking pump shaft seal 0鈥?240 0鈥?2,100 $1,680
Open ball valve 420鈥?480 3,680鈥?7,360 $2,944鈥?5,888
(12.5 mm)
Running hose (25 mm) 1,800鈥?4,000 15,770鈥?34,690 $12,616鈥?27,752
Broken pipe (50 mm) 4,200 367,920 $29,434
Note: Based on a constant flow over the year (i.e. 24 hours/day for 365 days).
Source: Adapted from FTJ (1998l)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
There may be numerous opportunities to increase the efficiency of water use
throughout the plant. To avoid spending too much money fixing problems that
yield little financial return, the company should undertake a survey of water
use. This will help identify the main areas where water is wasted, and the
potential economic value of addressing the problem.
Example 3: Reducing water consumption
R.H. Sheppard Company, Inc. in Hanover, Pennsylvania used large
quantities of fresh water for cooling metal parts during grinding
operations. The company installed a 60 kL closed loop cooling system
with temperature and bacteria controls, which saved 13 ML of water per
year and improved the grinding process. From its reduced coolant
disposal costs and savings in water costs, R.H. Sheppard Company
expects a two- to three-year payback period on its $US540,000
(A$830,000) investment.
In response to calls from the local water board to implement water
conservation during a major drought, Hopkinsons, a valve manufacturer in
the UK, halved its water consumption. Prior to the campaign, water use
was generally overlooked and averaged around 500 kL per week. Over
two years, this figure was reduced to around 220 kL per week.
The major changes that were implemented included the use of closed-
circuit cooling systems, electronic sensors for flushing urinals, tighter
control of evaporative cooling systems and staff awareness campaigns.
Annual savings from these measures were estimated to be 拢18,000
(A$45,000).
Sources: UNEP (1997) and FTJ (1996l)
1.3 Inventory Control
鈥楯ust-in-time鈥? purchasing and manufacturing systems are widely used in the
foundry industry and have been adopted by many Queensland companies.
These systems can greatly reduce inventory and warehouse costs and also
reduce the volumes of hazardous materials stored on site at any one time. This
reduces the risk and liability associated with accidental spills and the need to
dispose of out-of-date materials.
To control the distribution of hazardous and expensive chemical additives,
companies should consider locking stores and having a system where workers
can exchange empty containers for new supplies only on a one-for-one basis.
This will help avoid stockpiling or misuse of products and provide the possibility
of returning containers.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
The control of both incoming and outgoing materials may also be an area
where cost savings can be made. An engine manufacturer in the UK
redesigned its packaging system to use returnable and collapsible packing
frames. This system allowed the company to increase the number of units that
could be shipped per truckload from 30 to 44. Fewer than half the return
journeys were needed to return the packaging to the site. Overall transport
costs for these products were cut by around 10% (The Foundryman, 1999b). It
may be possible to work with suppliers to find ways to reduce or eliminate
packaging, for example by using returnable bulk bags or trays.
1.4 Staff Training
The benefits of a well-trained workforce can be an overlooked part of the
company鈥檚 Cleaner Production program. Training can benefit the company in
three ways:
鈥? Improving operator skills reduces operational costs by increasing
productivity and reducing errors and waste.
鈥? Training that is targeted at increasing general awareness of waste and its
implications can improve staff acceptance of waste minimisation techniques.
For example, a training company in the UK claims that the productivity of
shotblasting equipment can be increased by 80% through basic training
about the 鈥榙o鈥檚 and 鈥榙on鈥檛s鈥? of shotblasting (The Foundryman, 1999a).
鈥? An effective training program can empower workers and makes them feel
more valued by their company.
The best way to reduce spills is to train staff in the proper handling of materials.
There should be clearly established procedures for mixing chemicals, and the
responsibility for handling and mixing chemicals should be limited to a small
number of staff who are trained in the procedures. As well as reducing spills,
this will also improve the consistency of formulations.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2. Selecting Alternative Inputs
Key Points
Selecting alternative inputs provides a means of eliminating waste or improving
the efficiency of the operation 鈥榓t source鈥?. Foundries should carefully consider
each type of resource used in the process and calculate the true cost of the
material to the company in terms of the purchase costs, the disposal and
handling costs and the costs associated with quality problems (e.g. increased
scrap caused by inferior sand) and environmental problems (e.g. compliance
costs in managing odour from binders). Once the company knows the full costs
of each input and how it impacts on each stage of the operation, the company
will be able to set priorities for which inputs should be changed.
Some of the key questions to ask in relation to assessing the suitability of
alternative inputs include:
鈥? Can we work with scrap suppliers to improve the quality of the charge
material to avoid contamination?
鈥? Can we alter the metals and alloys that we use to improve casting quality?
鈥? Can we improve our materials testing procedures to improve product quality
and reduce waste?
鈥? Can we improve sand quality to improve the dimensional accuracy of the
cast?
鈥? Can we change the type of binders and other additives to improve cast
quality, increase reuse options, improve environmental performance etc?
鈥? Can we change the type of refractory material used in the process?
鈥? Can we change from solvent based coating systems to water-based
systems?
鈥? Can we alter the pattern or die materials to improve process performance?
鈥? Are there any new consumables (e.g. risers, sleeves etc.) that will improve
casting efficiency?
鈥? Can we change the type of energy used in the process to improve efficiency
and environmental performance (e.g. natural gas etc.)?
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
This section describes a number of alternative inputs that foundries are using
to reduce the environmental impact of their processes, and to improve casting
quality or efficiency. In addition to the ideas that are described in detail,
companies may wish to explore some of the following avenues to identify other
opportunities:
1. Purchase higher-quality moulding materials (e.g. sand with a low dust
and/or impurity content).
2. Alter the metals or alloys that are used, to improve casting quality.
3. Improve materials testing procedures, to:
鈥? improve product quality and/or reduce waste;
鈥? improve the acceptability of liquid metal prior to casting;
鈥? develop non-destructive, in-line, fast, reliable and accurate methods for
quantifying casting defects;
鈥? develop evaluation methods for ingot and as-cast chemistries and
properties (particularly for ferrous casting);
鈥? identify the presence of undesirable elements (e.g. antimony,
phosphorus, sulfur) and inclusions.
4. For ferrous foundries 鈥? explore the feasibility of working with steel scrap
suppliers to develop reliable sources of high-grade scrap (Environment
Canada, 1997).
2.1 Alternative Mould Coatings
Paints are used as the base for the refractory coatings on sand moulds and
cores to improve the surface finish by minimising sand contamination. The
environmental and operational problems associated with paint solvents are
prompting many companies to look at replacing these materials with non-
solvent alternatives.
Solvent systems such as alcohol, acetone and trichloroethylene offer a number
of advantages including: rapid drying by air or flaming; low gas levels after
drying; and minimal effect on the mould or core substrate. Problems associated
with solvent systems, however, include the generation of hazardous fumes,
occupational issues resulting in the use of flammable materials, and the
environmental costs and risks associated with handling and disposing of the
materials (The Foundryman, 1996a).
The two alternatives that companies can consider are water-based systems or
powder (dry) systems.
2.1.1 Water-based systems
Water-based coatings are being developed to better compete with alcohol
systems. Some of the problems that need to be overcome are high gas levels,
soft bond strength and longer drying times. Unlike solvent-based coatings,
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water-based coatings generate moisture, which is absorbed into the mould or
core. The surface of the paint becomes impermeable, making efficient drying
even more difficult. Modern coatings are continually being developed that have
reduced moisture ingress and faster drying times. Up to 50% reductions in
drying time over conventional acrylic paints have been reported. The four
common drying methods are forced air, microwave, infrared (see Example 4)
and dehumidification, with dehumidification being the slowest of these.
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Example 4: Infrared Drying
Decatur Foundry, a small-run jobbing foundry in the United States,
specialises in iron castings for electric-motor frames and parts as well as
pump components. A change form quick-drying, solvent-based coatings to
slow-drying, environmentally safer water-based coatings, created a
bottleneck in the production process.
The company installed an infrared/forced air unit as a replacement for the
conventional electric-resistance ovens. This resulted in an 85% decrease
in drying time. The new system heats the surface directly rather than
heating the air, so the system requires no warm-up time and does not
waste energy heating the air. Precision instrumentation allows more
control in the drying process.
Achievements:
鈥? Replacement of the first production line cost US$12,000 (A$18,400)
and reduced annual energy consumption by 120 MW.h, equivalent to
US$9,000 (A$13,800) .
鈥? Organic solvents were eliminated.
鈥? New units freed up floor space.
鈥? Eliminating the drying bottle neck reduced labour costs and increased
productivity, allowing Decatur to offer a very competitive turnaround
time.
鈥? Enhanced efficiency and productivity allowed Decatur to add two new
lines (including infrared units), increase employment by 13%, and
increase sales from US$5.9 million to US$10 million.
Progress Casting Group, in the United States, replaced its TCA solvent-
based paint with water-based coatings in 1994. The company used
13 tonnes of TCA at a cost of US$59,000 (A$91,000). This was replaced
with an equivalent amount of water-based coating at a cost of US$14,500
(A$22,000), resulting in a net materials saving of US$44,500 (A$68,500).
The company gained additional savings in reduced compliance and
disposal costs. The biggest obstacle was to develop an appropriate drying
system. The company evaluated high-intensity lights, drying tunnels,
infrared and microwave systems. Microwave and infrared were found to
be most efficient, but the non-selective heat of the microwave system
caused structural damage to the cores.
Sources: ACEEE (1999) and MNTAP (1994)
To date powder systems have been developed by Foseco, a major supplier of
foundry materials, for greensand systems and are based on the use of a resin-
coated powder (e.g. zircon). This material is tribostatically charged by blowing
the powder down a plastic rod. The charged material then seeks a conductive
medium (i.e. moist greensand) to earth the charge. These forces create a
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
sufficient bond to form a coating. During pouring, the heat from the metal
causes the resin to fuse together to give a fully bonded coating layer. This
technology is relatively new but, in the future, experience from other powder
coating practices may help to improve these systems further (The Foundryman,
1996a).
2.2 Water-based Shell for Investment Casting
Many investment casting operations (see Part 5) have successfully changed
from solvent-based shell mould systems to acrylic systems. Example 5
describes the experiences of one precision casting company.
Example 5: Water-based Investment Shell
A UK-based investment casting operation, MBC Precision Casting,
achieved significant savings by converting from an alcohol-based ceramic
shell production system to a modern water-based system.
The technology cost 拢17,200 (A$43,000) and at the end of the first year
the accumulated savings were 拢98,000 (A$245,000). The company also
avoided over 拢100,000 (A$250,000) in new VOC abatement technology.
The savings came from a number of sources including reduced slurry
evaporation losses, reduced scrap, shorter knockout times, lower rework
and virtual elimination of wax pattern relief. Poured weight capacity was
also improved, as was dimensional accuracy and control. There was also
a marked improvement in the shell shop working environment since
alcohol fumes were eliminated.
The company reported that the make-up costs for water-based slurry were
more than double those of alcohol-based coatings by weight. However,
the average number of coats required was reduced by around 18%. Slurry
costs per unit of metal poured, therefore, increased only from 拢0.29 per kg
(A$0.73) for ethyl silicate to 拢0.33 per kg (A$0.83) for the water-based
material. Also, the shell-to-metal ratio improved from 0.57:1 to 0.44:1
because heavier castings could be produced (up from 40 kg to 60 kg).
Sources: FTJ, 1998o and FTJ (1996h)
2.3 Improved Pattern Materials
Another avenue for investigation may be to consider changing the type of
pattern and mould materials used. Specialist coatings for moulds may improve
performance. For example, electroless nickel coatings on shell mould patterns
are reported to improve surface quality and increase the life of the pattern by
250鈥?300%. The natural lubricity of the surface finish aids in cast release and
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
improves surface quality. The patterns are also reportedly easier to clean, thus
increasing cycle time (FTJ, 1996n).
2.4 Improved Riser Materials
Risers are used in cast designs to provide the extra metal necessary to feed
the casting cavity, to compensate for shrinkage during solidification. Riser
sleeves, made from refractory materials, are designed to maintain the
temperature of the metal in the riser and to reduce the size of the riser cavity.
New sleeve technology may provide opportunities to improve cast design and
to improve metal yield. The most common type of riser used in foundries today
is made from fibrous refractory material. Non-fibrous, non-sand-based sleeves
have been developed and have been in use since 1996. These are reported to
provide greater dimensional accuracy and strength, low gas evolution and more
uniform insulating or exothermic properties (Metal, 1998a).
2.5 Alternative Energy Sources
Alternative fuels for melting are often less expensive and cleaner may be
available. Natural gas is typically a better option can fuel oils from a reliable
source is available. If fuel oils are used, lower grade oils may be available.
Petroleum distillated will result in lower particulate emissions than heavier
grade fuels. Chose a low-sulfur or low-nitrogen fuel, natural gas reduce air
emissions further. Proper maintenance of furnaces will also help reduce
emissions (USEPA, 1998).
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3. Improving Metal Yields
Key Points
Improving metal yield offers many foundries a significant potential to increase
the efficiency of their operations, particularly in terms of energy use.
Conventional sand casting operations have the most potential to increase
metal yield. These improvements can increase efficiency in a number of ways
including tonnes of usable castings per melt; per tonne of sand; and per hour of
labour. The time required for handling reject and scrap material and for
recycling operations can also improve as can emissions from the foundry.
Foundries should consider the potential costs and benefits of improving metal
yields as fully as possible.
Some of the key questions to ask in relation to improving metal yields include:
鈥? How many tonnes of metal do we melt for each tonne of usable castings?
What are the major areas of loss (e.g. melt losses, spilt metal, pigged metal,
runners and risers, reject castings, or grinding losses)?
鈥? Can any of these areas of metal loss be reduced by:
鈥? minimising metal spills, over- or under pours thorough precision pouring
techniques?
鈥? redesigning the gating system to make it more efficient?
鈥? using casting simulation technology to improve cast design and
solidification properties?
鈥? working with our customers to redesign the casting to reduce it鈥檚 weight
or improve its casting characteristics?
鈥? minimising grinding losses or even eliminate some fettling operations
from the foundry?
鈥? using metal filtering, direct pouring techniques or other methods to
minimise inclusions in the metal?
鈥? Can we redesign, optimise or change the casting process used to increase
the metal yield?
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Metal yields are expressed as the ratio of the amount of product sold to the
amount of metal melted. Many casting processes, particularly conventional
sand casting methods, are inherently wasteful in terms of metal yields: the
world industry average for iron foundries is around 50鈥?60% (FTJ, 1996c).
There are many reasons for this. Yield depends partly on the type of casting
(see Table 3) and partly on the casting process used. Precision casting
processes, such as investment casting and die casting, achieve relatively high
yields in comparison to most traditional sand casting methods.
Table 3: Typical Yields for Different Castings
Casting Metal yield (%)
Heavy grey iron casting 鈥? simple shape
Medium-sized grey iron casting 鈥? jobbing or small batch 65鈥?75
production
Small to medium-sized grey iron engineering and municipal
castings 鈥? mechanised, volume production
High integrity small to medium-sized grey iron engineering
castings, simple design 鈥? mechanised, volume production
High integrity small to medium-sized grey iron engineering 55鈥?60
castings, complicated or heavily cored design 鈥?
mechanised, volume production
Medium-sized ductile iron castings, jobbing or small batch 50鈥?60
production
Small grey iron castings 鈥? mechanised, volume production
Small ductile iron castings 鈥? mechanised, volume 40鈥?50
production
Source: DETR (1999)
Gating systems (i.e. runners, risers and sprues) are often large, and sometimes
larger than the actual product cavity. Wall thicknesses are sometimes over-
specified to compensate for porosity and other metal quality problems. The
number of units produced is often over-specified to compensate for reject
products and customer returns. All this means that, for every tonne of metal
sold, around 2 tonnes are melted (FTJ, 1997d).
While the bulk of this excess metal is collected and remelted, it represents a
significant cost to the foundry in the following ways:
鈥? energy used in melting and holding the metal;
鈥? capital costs for unnecessary metal handling capacity;
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? increased fettling costs;
鈥? unnecessary metal collection and sorting time;
鈥? increased maintenance of equipment;
鈥? lost time that could be used for value adding activities; and
鈥? customer relations issues.
Many foundries underestimate the true cost because they do not account for all
of these sources of cost. Even so, the direct costs of energy are often sufficient
to generate interest in making improvements in this area. Typical iron foundries
using electric induction furnaces use between 500 and 800 kW.h of electricity
for each tonne of metal melted, depending on the scale of operation and the
melting and holding practices employed (FTJ, 1997e). At an average of 7 cents
per kW.h in Australia, this equates to between $35 and $56 per tonne.
The Queensland casting industry produces over 80000 tonnes of castings each
year. Assuming an average melt efficiency of 600 kW.h per tonne ($42 per
tonne @ $0.07 per kW.h) and a metal yield of 50%, the industry is spending in
excess of $3.3 million melting metal that does not end up in the final product.
For an average foundry, producing 7000 tonnes of castings in a year, this
would equate to nearly $300,000. The melting costs over a range of production
rates and metal yields are shown in Figure 1.
Figure 1: Melting Costs of Iron Foundries using
Induction Furnaces
Metal yield
1,600
3:1
1,400
2.5:1
1,200
Energy cost ('000 $)
2:1
1,000
800 1.5:1
600
1:1
400
200
0
2,000 4,000 6,000 8,000 10,000 12,000
Annual production of finished castings (tonnes)
Note: This figure shows the costs of melting in an iron foundry using
an induction furnace. The ranges of annual production and metal
yields shown are typical for Queensland foundries. This analysis
assumes a melting efficiency of 600 kW.h per tonne of metal melted
and an electricity cost of $0.07 per kW.h.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
A realistic target for Queensland foundries may be to improve metal yield by
around 20% (Metal (1997b) and FTJ (1997d)). This could mean a saving of
over $600,000 for the Queensland industry and $60,000 for a 7000 tonne
foundry.
Metal yields may be reduced in a number of areas in the foundry process. The
benefits that could be gained by implementing improvements will vary between
foundries. Therefore it is important for companies to undertake their own mass
balance for metal, to identify the true cost of metal loss to the company and the
key sources that can be addressed most effectively.
Improving metal yield often requires an integrated approach to ensure that
improvements in one area lead to an overall improvement in operational
efficiency. Companies wanting to improve yield should analyse the whole
process to identify the main causes of waste and develop an integrated
improvement strategy.
The Energy Efficiency Best Practice Program in the UK has prepared a
publication titled Achieving High Yields in Iron Foundries (DETR, 1999). Figure
2 is derived from this publication, and provides a simplified model of the
foundry process, showing the major areas of metal loss. Using a mass balance
approach to account for metal yields and metal loss is an essential first step in
identifying the key opportunities for improvement.
Figure 2: Metal Mass Balance of a Typical Foundry
Metal lost
Metal lost
Metal lost
Melting Spilt
Grinding
losses metal
losses
Metal
New Metal Metal Good
Total
in
metallic poured in castings
metal
good
raw into gross dispatched
melted
casts
materials moulds casts to customers
Metallic
returns
Scrap
castings
Runners
Pigged
metal
Source: DETR (1999)
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3.1.1 Minimising Melting Losses
Melting losses as high as 3% have been reported by practising foundries (FTJ,
1997g). These losses are mainly a result of oxidation, slag removal and
sampling operations. Minimising this loss may be achieved by:
鈥? minimising contamination in the charge;
鈥? accurate charge make-up and weight;
鈥? optimising stirring practices to minimising slag formation;
鈥? minimising unnecessary superheating; and
鈥? selecting and maintaining appropriate refractory linings (DETR, 1999).
In some cases it may be possible to recover metal from slag, either in the
foundry operation or in another process. One company鈥檚 experience in metal
recovery from slag is descried in Example 6.
Example 6: Metal Recovery from Slag
J. McIntyre Aluminum Ltd, in the UK, has dramatically increased metal
recovery from its aluminium slag by installing two skimming, pressing and
cooling systems. The company produces 30000 tonnes of castings
annually and generates 6000 tonnes of slag each year. The system,
known as a 鈥楾ardis鈥? (thermal aluminium recovery from dross in situ),
achieves 48% recovery of the metal from the slag. Before the
development of this system the company used a conventional cooling and
cold processing route to recover metal from the slag. This system
produced a 28% return to sow; thus the new system achieved a 20%
increase in recovery. The company claims that similar results could be
achieved with all types of aluminium slag.
Source: FTJ (1996e)
3.1.2 Minimising Spilt and Pigged Metal
Metal can be spilt during transfer to the melting furnace, the holding furnace,
the pouring ladle and finally the flask. These losses can be minimised through
better training, improved procedures and automation of the pouring process.
Excess or poor-quality metal is typically pigged at the end of the run. Although
it will be remelted this represents a loss in terms of energy, labour and a minor
amount of metal. In some cases it may be possible to return molten metal left in
the ladle to the furnace, rather than pigging it out. This will reduce some of the
energy loss.
To ensure metal quality, and to ensure that end production is not held up, most
foundries melt more metal than is required for a particular production run to
compensate for losses.
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The amount of excess metal can be reduced by better matching metal demand
and supply. Improving the efficiency and consistency of the pouring process
will allow greater predictability of metal demand. Reducing holding times by
better timing the melts to coincide with production can reduce energy use and
reduce the risk of metal cooling to a point where it is unusable (DETR, 1999).
Precision or automatic pouring systems (see Example 7) improve metal yields
by delivering an appropriate and consistent volume of metal to each mould at
an optimal flow rate. The pouring location, in relation to the sprue, can also be
controlled to improve the fill-out consistency. By doing so, over-pours and
short-pours are eliminated, slag and other inclusions are reduced and casting
quality is enhanced (FTJ, 1998h). Cycle time can also be significantly reduced,
which is an important consideration for repetition foundries.
Example 7: Precision Pouring
The LaserPour system from Selcom Inc has been demonstrated to be cost
effective in some iron foundries. Selcom claims that a typical iron foundry,
with an average mould weight of 22.7 kg, 350 moulds per hour and
350000 tonnes of metal melted annually, can save over US$225,000
(A$346,200) in remelt costs annually and US$125,000 (A$192,000)
annually in other savings including labour, increased profit in added
output and reduced downtime. The company claims a further 15%
improvement above this with its latest LaserPour IV system.
Chrysler Foundry, a supplier of engine blocks, installed four LaserPour
systems to replace the previous teach-in pouring method. After
overcoming some additional installation problems, which cost in the order
of US$15,000鈥?20,000 (A$23,000鈥?31,000), the foundry experienced a
significant increase in pouring consistency. This reduced the gross weight
of the casting by around 3.2 kg per sprue cup poured, and reduced the
overall scrap rate by around 510 tonnes. The monetary savings were
approximately US$1 million (A$1.5 million) during the foundry's 1994鈥?95
fiscal year.
Auburn Foundry, in the United States, pours up to 1600 tons of grey iron a
day at its two plants. The company installed a LaserPour laser-controlled
molten-metal-pouring system. The installation of new systems resulted in
cycle-time reduction and generated a 6鈥?8%production increase at one
plant. Depending on the weight of the job, cycle time was between 7 and
12 seconds per mould. This was reduced by between 0.5 and 1.7
seconds. At 6000 to 8000 moulds per day for each line, and multiple lines
at both plants, this amounts to a high potential for savings.
Sources: FTJ (1998h); Quality (1996); and Quality (1998)
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3.1.3 Minimising the Weight of Castings
The gross and net weight of castings are often over-specified to compensate
for metal quality problems, and due to uncertainties in the pouring and
solidification process. This means that more metal is melted and poured that
necessary.
Efficient casting design is an important component of increasing metal yield.
Careful design of castings and gating systems can significantly reduce both the
gross and net weight of the casting, thereby increasing metal yields. Cast
redesign also has an important impact on the following:
a) Box yield 鈥? the ratio of net weight of castings to gross weight of metal
poured. Increasing the number of units per box typically allows the relative
size of the gating system to be reduced. Casting design studies indicate
that adding an extra unit to the box can increase box yield by between 50%
and 60%.
b) Box design 鈥? the size and shape of the box used. This can also reduce the
volume of sand per casting.
c) Sand yield. Increasing the volume of metal in the box reduces the amount of
sand that is required per tonne of product (DETR, 1999).
The major concern about reducing the size of the gating system is the risk of
reducing product quality as a result of poor fill-out and shrinkage. The use of
casting simulation software can help in redesigning the gating system while
maintaining good casting quality (see Example 8). Industry experience shows
that, depending on the current geometry and gating system used, cast weight
can be reduced by as much as 30% without affecting cast quality. Reducing the
size and complexity of gating systems can also reduce fettling time and the
handling of metal for recycling (FTJ, 1997i).
Improved metal quality, direct pouring and casting simulation can all help to
reduce the net weight of the actual casting. The increased confidence that
these systems provide can allow the designers to specify lighter sections (e.g.
reduce wall size). Some foundries use simulation techniques to identify
opportunities to reduce dramatic changes in section size. Such changes can
lead to quality problems and require far larger gating systems. Changing
casting design requires a close relationship with customers, and is typically
harder for jobbing foundries to organise than for captured foundries (DETR,
1999). There can be flow-on benefits to the customer in terms of a cheaper,
higher-quality product. Further benefits can also flow to downstream users (e.g.
lighter equipment, which costs less to operate) (The Foundryman, 1997a).
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Example 8: Reducing Casting Weight Using
Simulation Technology
Fishercast Ltd, a producer of steel valves, in the UK, has been using
traditional design techniques based on modulus techniques (i.e. the use
of standard engineering rules and formulas to calculate the appropriate
size of the casting). The company invested in casting simulation software,
MAGMASOFT, to evaluate the potential to redesign its castings to reduce
their gross weight.
The company identified the products where they thought the major
savings could be made. One steel valve body that was selected had a
pour weight of 2330 kg. After using simulation software, they were able to
produce a sound casting with a pour weight of 1880 kg, nearly a 20%
reduction in metal use. Fettling time was reduced from 10.5 hours to 4.3
hours and total production costs were reduced by 12%.
Source: FTJ (1997i)
3.1.4 Minimising Grinding Losses
Fettling is probable the least favoured job in most foundries and, as a result,
foundries often report difficulties in maintaining good-quality staff in this area.
Fettling can account for as much as 20鈥?30% of the total direct costs,
particularly for iron foundries. Added to this are the costs of time lost to injuries,
recruitment and organisation problems, which can greatly increase the actual
cost of these activities (FTJ, 1998n). Fettling is also a significant source of
metal loss, which can be difficult to recover cost-effectively. See Example 9
which discusses one company鈥檚 experiences in minimising grinding in its
operation.
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Example 9: Rapid Grinding Systems Minimise
Grinding Waste
A.W. Bell, a precision investment casting foundry in Australia, has
developed a rapid grinding systems, the RGS430, in response to a
perceived lack of appropriate technology to minimise waste from their
fettling area.
The belt finishing machine incorporates an indexable feed table attached
to a swing arm. Parts are mounted into the grinding fixture to achieve
consistent, repeatable grinding. The movement of the arm and grinding
pressure are preset for the part and type of alloy being processed. The
benefits of this change are numerous:
鈥? The operator鈥檚 role has changed from being the actual grinder to being
a part loader and unloader, since the machine does all the grinding
work.
鈥? Operators tend to use grinding belts unevenly. The grinding machine
uses all the parts of the grinding belt equally, ensuring even wear and
maximum belt life.
鈥? Studies have also shown that, because operators are unable to apply
consistent pressure on the grinding face, the abrasive material tends
to go dull. The consistent pressure applied by the machine keeps the
abrasive material sharp, which also increases belt life.
鈥? The automated system ensures consistent grinding and eliminates
operator issues such as over-grinding and grinding errors. Scrap rates
are greatly reduced.
鈥? Safety is significantly improved because operators are no longer
directly doing the grinding, thus reducing the risk of repetitive injury.
The working environment is also improved.
Tests comparing the efficiency of the machine against a skilled operator
showed impressive improvements 鈥? a 438% improvement in productivity
over the shift and a 75% reduction in belt usage. In an 8-hour shift the
operator used six belts to finish 800 parts, whereas the machine used the
same number of belts but finished 3500 parts in the shift.
Source: Metal (1996a)
Another concern about the fettling process is that it is largely a non-value-
adding activity. With the increasing need to reduce costs in the industry, many
foundries are looking at ways to reduce or even eliminate the fettling stage.
Some have found that this can be achieved by improving both upstream and
downstream processes in the following ways:
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
a) Improving the casting process may reduce the need to fettle.
Casting processes such as lost foam or investment casting, which achieve
鈥榥ear-net鈥? or 鈥榓s-net鈥? castings (i.e. close to the size of the final product so
that it requires less fettling and cleaning), can greatly reduce the need to
fettle. Conventional casting techniques are also constantly being improved
to achieve similar benefits. Gating systems can also be redesigned, as
discussed in the previous section.
b) Some fettling processes can be combined into the machining stage.
In some cases, fettling may be unnecessary. Often parts are over-fettled by
operators who want to do a good job. Some burs may be purely cosmetic
and be effectively removed in the machining process. Improvements in
these areas have been found to reduce fettling time by around 20% without
affecting product quality or increasing machining costs (FTJ, 1998n).
Changes to procedures, including quality control, would be required to
develop appropriate standards and coordinate the actions of operators in
each process. Machining tools are being developed that are more tolerant
of unfettled parts, so the line between fettling and machining is becoming
increasingly blurred.
c) Many of the remaining fettling processes can be automated.
Robotic fettling cells have been developed that can automate some fettling
functions. These systems can reduce the space needed for the fettling area
and create a more continuous flow of product through the area. Robotic
systems can use heavier grinding equipment which can reduce grinding
times. The systems can be enclosed so that noise and emissions can be
more effectively controlled and higher levels of metal recovery can be
achieved. Experience in companies suggests that cycling times can be
reduced by 50鈥?75%. With most castings, manual fettling is typically not
eliminated entirely and the systems are most suitable for repetition
foundries (FTJ, 1996g).
Used in concert, these three strategies may eventually 鈥榮queeze out鈥? manual
fettling processes from many casting operations (see Example 10).
Example 10: Eliminating Fettling from the Foundry
Process
The Swedish Foundry Association has been working to eliminate fettling
from the foundry process. The two companies discussed below have
successfully incorporated fettling into the machining process. Osterby
Steel Foundry AB produces fully finished castings. The company
identified a range of flexible machine tools, multi-operation machines and
lathes. For example, a five-spindle milling machine was purchased for
milling pump wheels. Initially the fettling of pump wheels required
120 hours of hand grinding.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Fettling time has been reduced to 35 hours of automatic grinding, with an
additional 25 hours for hand milling. Across the product range, fettling
time has been reduced by between 2 and 28 hours per unit. The company
reported that most of the barriers to this improvement were organisational
rather than technical. Communication problems between departments,
wage issues, departmental under-utilisation, and scepticism among staff
are cited as key barriers.
ITT Flygy AB, a manufacturer of iron and chromium submersible pumps,
has increased production by 60% while maintaining the same number of
fettling staff. As well as implementing job rotation to reduce fettling
accidents and to retain staff, the company has implemented a range of
changes designed to eliminate fettling. These include:
鈥? improved pattern design and equipment;
鈥? incorporating a parting rib, which does not require fettling, instead of a
parting flash in cast sections (where no structural problems would
result). Where a parting flash cannot be eliminated it is transferred to
surfaces that will be machined automatically;
鈥? standardising the angle of the parting burr to simplify fettling and allow
automation;
鈥? changing core design to eliminate gluing, which can create a mismatch
and require fettling;
鈥? changing the gating systems (to the Connor gating system) to
incorporate long, thin in-gates that are easier to knock off and
machine.
The benefits that have been gained include:
鈥? a reduction of fettling cells from nine to four with greater total output;
鈥? improved product quality, shorter machining times and lower
manufacturing costs;
鈥? reduction of the need to reassign staff due to repetitive injuries from an
average of six staff per year to zero.
In addition:
鈥? The majority of castings no longer need fettling. Fettling time for the
remaining casting has been reduced, often by more than 70%.
鈥? Fettling has been eliminated in the design of all new castings.
Source: FTJ (1998n)
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3.1.5 Minimising Scrap
Reject product or scrap can be very costly to the foundry operation in terms of
reduced production efficiency and, in some cases, loss of reputation if
production schedules are held up or faulty product is shipped.
Scrap should be 鈥榙esigned out鈥? of the process wherever practical. More
efficient melting practices can reduce inclusions and porosity in the metal,
reducing the need to reject poor-quality product, thereby reducing waste at
source. It can also reduce the need to compensate for poor metal quality in the
casting design for higher box yields to be achieved (FTJ, 1997i).
Good inspection processes should be maintained to remove reject product from
the process as soon as possible to avoid further processing. All incidents of
scrap should be recorded, measured and investigated to identify and address
problems. All reject product should be carefully segregated to ensure that it is
not shipped to customers by mistake and is properly recycled.
Reducing the reject rate can also lead to significant savings in a range of
areas. If a foundry that produces 5000 tonnes of good product reduces its
reject rate from 6% to 5%, it would result in a reduced demand of 137 tonnes of
molten metal. In turn, this would lead to:
鈥? a reduced metal charge of 141 tonnes (assuming a 3% melt loss);
鈥? a reduction of around 85 MW.h of electricity (at 600 kW.h per tonne) for an
electric induction furnace, saving over $5,900 (at $0.07 per kW.h); and
鈥? a reduced slag production of 5.6 tonnes (assuming 4% slag) (FTJ, 1997g).
There will also be benefits in other areas 鈥? most prominently, reductions in
labour, sand use, reclamation and dust generation (DETR, 1999).
3.1.6 Casting Simulation
Casting simulation technology is an emerging technology that is being used to
increase the efficiency of casting design processes (i.e. gating design).
Traditional foundry practices in this area range from simple adaptations of
standard designs to using engineering methods to estimate the appropriate
dimensions of the cast and gating system.
Simulating metal flow and solidification can improve casting design and help
demonstrate the cost effectiveness of different design variables. This can be
achieved prior to the casting and can significantly reduce lead times.
Being able to make a detailed prediction about casting quality, given a
specific process design, prior to the actual production of the casting,
provides benefits which should be obvious to any operating foundry
person
Metal Asia (1998d)
All foundries, to some extent, experience problems with the casting design
process. These include quality issues (e.g. porosity, shrinkage and strength),
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
which result in some level of scrap, and commercial issues such as lost
business resulting from poor quality, long lead times or inability to make early
predictions and guarantees of quality. Some of the design improvements that
can be achieved using casting simulation systems include:
鈥? optimisation of gating systems;
鈥? reductions in high-velocity melt erosion;
鈥? optimisation of filling times;
鈥? adequate venting in die castings;
鈥? reductions in slag entrapment;
鈥? optimal use of filters;
鈥? optimisation of casting method;
鈥? optimisation of feeder size and position;
鈥? optimisation of casting removal times;
鈥? improved box yield;
鈥? effective use of chills; and
鈥? reduction in heat impact to cores (MAGMA, 1999).
In summary, the above improvements lead to reduced scrap rates, higher
quality and greater predictability. This can also impact on the efficiency of the
process in terms of metal yield, energy use, process flow, product quality and
reduced fettling time.
To date, casting simulation technology has been adopted only by around 10%
of the foundries in the developed world. There is some level of scepticism
about the potential of this branch of engineering. This is largely due to a
number of technical, economic and perceived barriers to using the systems.
The cost of the technology is relatively high and many foundries do not have
the knowledge necessary to choose the most appropriate system (FTJ, 1998k).
The quality of the prediction depends on the quality of the input data and the
judgment of the engineer to be able to select the most important criteria. In
practising foundries, a balance is needed between undertaking a detailed
analysis and making a timely commercial decision (Metal Asia, 1998d).
There are also some unrealistic expectations as to what the technology can do.
The models are still based on an incomplete knowledge of the microprocesses
that occur during the pouring and solidification process. It is not currently
possible, therefore, to eliminate all quality problems from the casting process.
Fortunately two of the major quality issues, porosity and shrinkage, are
relatively amenable to prediction (Metal Asia, 1998d).
The technology is complex and will not be a 鈥榤agic potion鈥? for the foundry
industry but, when used appropriately, it has been shown to create significant
net benefits.
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Experience from the industry indicates that the cost of implementing the
technology can often be justified on the basis of reduced scrap alone. For
companies that experience high reject and scrap levels on major product lines,
the cost of modelling can often be justified after only one job (Metal Asia,
1998d). If problems are being experienced on just a few high-value lines, or the
company is too small to justify developing an in-house capability, the company
could consider outsourcing or entering a joint research and design project with
a professional modelling group.
3.1.7 Metal Filtering
In an effort to improve metal quality, increase productivity and move towards
zero defects, many foundries are using filters to remove dross, slag and other
impurities from the melt. This improves the metallurgical properties of the casts,
improves surface finish, achieves greater yields and reduces operating costs.
Metal filtration technology has improved greatly in recent times (see Example
11). They are becoming more refractory, less prone to breakage, more tolerant
of thermal shock and extreme pouring temperatures and less expensive.
Example 11: Filtering Metal
Auto Alloys Foundries, in the UK, have achieved major savings in the
cost of the metal alloys used. These savings have come from increased
metal yields, achieved by redesigning the runner system. As an example,
one nickel/chromium alloy fan head casting, with a net weight of 29.5 kg
as cast, originally required 58 kg of liquid metal. The company now
pours directly into the central boss through a ceramic filter, allowing riser
size to be reduced. This has reduced metal demand to 39 kg 鈥? a 32%
reduction. The reject rate was also reduced by 5%. The savings have
been estimated to be 拢14.66 per unit (A$37). The company has also
reduced design time without loss of quality for many of their products.
Overall, the company鈥檚 reject rate has been reduced from 6% to 1%.
Swan foundry, an iron foundry, also in the UK, has also reported
reasonable savings. The ability to simplify the runner system has
allowed the company to fit more castings in a box for many of its
products. This has greatly increased metal yield. For one of its products,
a 12000 unit per year 10.8 kg ductile iron housing, the company
estimates that the unit savings for increasing the number of units in the
box from one to two is in the order of 拢2.20 (A$5.50 per unit or A$66,000
per year).
Source: FTJ (1997j)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
3.1.8 Direct Pouring Techniques
Direct pouring of metal into sand moulds has been practised throughout the
history of casting. This technique, however, leads to sand erosion and
carryover of slag into the casting. In order to overcome this problem, many
sand casting operations use sprue cups to reduce the metal contact with the
sand. Complex runner systems have also been designed, including pouring
brushes, downsprues, runner bars and in-gates, to reduce turbulence and
impede the flow of inclusions into the mould cavity (Metal Asia, 1999b).
In the past five years, direct pouring techniques have improved to the point
where the sprue cups can be eliminated and runner designs can be greatly
simplified. In many cases pouring brushes, runners, filter prints and in-gates
can be eliminated without compromising cast quality. The new direct pour
devices, supplied by Foseco, are a combination insulating sleeve and metal
filter that replaces a traditional pouring cup and acts as a feeder (Metal Asia,
1999b).
The major benefits of these techniques include the following:
鈥? Quality improvements result from filtering, which more effectively removes
external inclusions than gating system flotation, and a reduction in
turbulence. Faster filling rates can be achieved leading to reduced thermal
gradients, reduction of cold metal defects and more directional solidification.
鈥? Yield improvements, resulting from simplified runner design, can greatly
reduce the poured weight. Light-weighting (i.e. reducing the net weight of
the actual product) the product may also be achieved due to improved metal
quality. The simplified runner system can allow more units to be included in
a single box and more units to be produced in a single melt. These changes
all tend to reduce energy use. Better mould utilisation can also lead to
reduced sand use.
鈥? Productivity improvements through faster pour rates lead to greater
throughput. Rejects and rework can be significantly reduced and labour
costs for mould handling, knockout, fettling, and sand handling can also be
reduced.
鈥? Reduced fettling, through better surface finish and fewer gating marks,
reduce the need for grinding and welding repairs (Metal Asia, 1999b).
Australian foundries (see Example 12) report that by using these techniques
they are achieving, on average, a 20% yield improvement, a rejects rate of less
that 1% and minimal repair work (Metal, 1997b).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 12: Direct Pouring
An Australian foundry, owned by Foseco Pty Ltd, produces a conveyer
casting in an aluminium alloy (RH Si7 Mg. While it is only 3.5 kg, it must
be able to withstand a high load (1.2 tonnes). In order to guarantee the
loading specification, the company has to ensure equal distribution of
molten metal and directional solidification of the casting. This meant that
the company used a complex runner system, including two downsprues
and six in-gates and a series of risers. The reject rate was high 鈥? around
8% 鈥? due to inclusions created from the turbulent flow.
By using foam filters, a non-turbulent flow could be achieved and oxides
and inclusions could be trapped more effectively. This allowed the gating
system to be greatly simplified. The use of an insulating sleeve ensures
that the metal remains in a liquid state long enough to allow sufficient
feeding into the cast cavity. The reject rate was reduced to 1% and the
cost per unit was reduced from $82 to $67 鈥? an 18% improvement.
By using direct pour techniques, the gross weight of another product (with
a net weight of 53 kg) was reduced from 82 kg to 69 kg. This reduced
metal costs from $296 to $249. Sand use was also reduced somewhat,
from 169 kg to 159 kg per unit, reducing the cost of sand from $18.77 to
$17.05 per unit. Cost for consumables (i.e the filter and sleeve) increased
from $19.11 to $28.54 per unit. In total, the company saved over $39 per
casting or 11% over the original method. This estimate did not include
savings in fettling time and rework, which were also considered to be
significant.
Source: Metal Asia (1999b)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
4. Improving Energy Efficiency
Key Points
There are many opportunities for improving energy efficiency in most foundries.
Some of these, such as optimising the efficiency of ancillary services can be
achieved at minimal cost and make a valuable improvement to the bottom line.
Reports from many foundries suggest that energy efficiency is one of the most
significant Cleaner Production options still to be addressed in the industry.
Foundries should undertake an audit to establish the full cost of energy to the
company and the major demands on energy in the process. This will help
prioritise improvement strategies.
Some of the key questions to ask in relation to energy efficiency include:
鈥? Have we undertaken a recent detailed assessment of energy efficiency in
the foundry?
鈥? Can we benefit from implementing an energy monitoring program to manage
energy use for either the whole foundry or for major equipment such as
furnaces?
鈥? Can we optimise the efficiency of our metal melting and holding processes
(e.g. 路 change technology, better insulation, use protective covers over the
melt; put a cover on the pouring ladle)?
鈥? Can we optimise the efficiency of the ancillary services in the operation?
鈥? Can we benefit from investing in automatic energy control systems to shut
down equipment when not in use?
鈥? Can we develop greater staff awareness of energy efficiency and run an
effective 鈥榮witch-off鈥? program?
鈥? Can we improve the ladles and refractory materials used in the furnaces
and to improve energy efficiency?
鈥? Can we recover energy from any sources for reuse elsewhere in the
foundry?
鈥? Can we benefit from investing in energy efficient equipment and up-grading
old equipment (e.g. lighting, ladle preheating, sand reclamation, furnaces
etc.)?
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Energy is a major cost for all foundries, typically accounting for around 10% of
the total operating costs (FTJ, 1997e). Furnaces use a significant proportion of
the energy consumed in foundries, around 60% for typical iron foundries.
Figure 3 shows typical energy demands for an iron foundry as reported in a
survey undertaken by the ETSU (FTJ, 1997b).
Figure 3: Typical Energy Demand 鈥? Iron
Foundry
Other (incl. heat
treatment)
Compressed 10%
air
4%
Ladle heating
5%
Lighting and
heating
9%
Melting and
Moulding and
holding
core making
63%
9%
Source: FTJ (1997b)
The survey reported that, in 1994, the UK ferrous foundry industry used 10.5
GJ per tonne of saleable product which was a reduction from 12.2 GJ per tonne
in 1991. Mixed metal non-ferrous foundries were found to have higher average
energy consumption per tonne of product and also a greater range between the
best and worst practice 鈥? between 32 GJ per tonne and 131 GJ per tonne.
This means that the companies with lower energy efficiency were at a
tremendous cost disadvantage in relation to their competitors (FTJ, 1997b).
Melting and holding were found to be key targets, due to the high energy
demand in these areas.
The energy consumed in the melting process is largely proportional to the
amount of metal melted (DETR, 1999). Therefore improving metal yield (see
section 3) is a key strategy in reducing overall energy consumption.
Non-melting functions in non-ferrous foundries were typically found to be
higher than for ferrous foundries 鈥? around 50% of total energy demand as
opposed to around 33% for ferrous foundries. Sand reclamation is becoming an
increasing source of energy demand (FTJ, 1997b).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Energy cost savings may come from increasing the efficiency of equipment
(e.g. furnaces, compressors), from improving the efficiency of production
processes (e.g. increasing metal yields and reducing sand demand) or by
reducing the cost of energy (changing energy source, changing tariff or timing
of energy consumption).
The area of energy efficiency improvements is a good candidate for Cleaner
Production efforts since significant gains can be made, often with relatively
minor capital expenditure. The potential savings may, in fact, be sufficient to
warrant dedicating a staff member or forming a team to investigate energy
efficiency throughout the operation.
4.1.1 Energy Auditing and Monitoring
Energy monitoring can help identify areas of inefficiency and reduce the overall
cost of energy (see Example 13). Monitoring, generally in the form of an energy
audit, is an essential first step to improving the energy efficiency of the
operation. It is important know the true costs of the current practices at the
outset in order to be able to assess the viability of improvement options.
Monitoring systems can be used to measure energy use by major equipment
such as furnaces, and can also be used to control energy use on a site-wide,
ongoing basis. A well-designed energy-monitoring system can help pinpoint the
underlying causes of inefficiency and help determine the potential cost savings.
This will allow the company to evaluate the cost effectiveness of different
management practices. For example, companies that use scrap from a range of
sources can evaluate which materials achieve the highest melt efficiencies
(The Foundryman, 1997d).
Once a monitoring system has been established, it will also help the company
to track improvements and measure the impact of changes within the foundry
on energy efficiency over time.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 13: Energy Monitoring
Lucy Castings, in the UK, which melts 20000 tonnes of metal annually,
implemented energy-monitoring technology that provides a minute-by-
minute analysis of power consumption in the foundry. The company has
formed an agreement with its electricity supplier to receive a low tariff if it
remains within an agreed energy limit. As well as involving load
management to ensure the company does not exceed this limit, the
system has helped identify opportunities to improve energy efficiencies.
The company鈥檚 energy bill has been reduced by around 30% from
拢1,000,000 (A$2.5 million).
Sandwell Castings, another UK company, installed a dedicated power-
monitoring unit on its electric induction furnace to measure the specific
energy consumption (SEC) which, it was believed, was worse than
industry benchmarks. The company conducted a trail using the meter to
monitor energy use on a minute-by-minute basis. This analysis uncovered
a number of inefficient practices, including:
鈥? failures to operate the furnace under high power;
鈥? lengthy holding times while waiting for compositional checks and
alloying additions;
鈥? lengthy holding periods while waiting for transfer to the launder or
transport ladle;
鈥? raising of melt temperatures to unnecessarily high levels.
The company reduced the average melt SEC by 57 kW.h per tonne,
saving the company around 拢7,000 per year (A$17,500). The equipment
paid for itself in around 6 months.
The G. Clancy Limited foundry in the West Midlands, UK, implemented an
integrated monitoring and scheduling system to identify batch melting
costs and allow comparisons between furnace charging and scheduling
methods. This has helped optimise charging procedures, slagging
practices, cold start routines and relining procedures. The capital
investment was 拢30,000 (A$75,000) and the resulting energy savings paid
for the equipment in less than 6 months. As an example of the
improvements, energy input to one of the 10-tonne furnaces was reduced
from 654 kW.h per tonne to 553 kW.h per tonne 鈥攁 15.4% improvement.
Sources: FTJ (1998f); The Foundryman (1997d); and FTJ (1997c)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
4.1.2 Improvement Opportunities
Many foundry operations, like other industrial operations, assume that there are
few options to minimise energy use in the process other than investing in
expensive new technology. However, many case studies from the foundry
industry suggest that most companies can achieve significant savings in this
area by optimising existing systems and by making minor system upgrades. An
extensive study of furnace efficiency by the ETSU in the UK has found that
surprisingly few of the foundries had optimised their furnace processes. They
concluded that most companies could reduce their total energy bills by between
10% and 30%, reducing total operational costs by between 1% and 3%. Other
flow-on benefits are often achieved as a consequence, such as higher metal
yields, improved metal quality, reduced labour and maintenance costs and
better environmental performance (FTJ, 1997e).
While there are gains to be made in most foundries, they are not necessarily
easy to achieve. As with any technology, foundries try to optimise the efficiency
of melting practices by balancing a wide range of interrelated factors such as
fuel and operating costs, metal production demands, environmental
performance and costs, legislation and other operational, managerial or
political considerations (FTJ, 1998a). Therefore, making a change in one area
may have an adverse impact on other areas.
This indicates that the best approach to improving energy efficiency is to
consider the issue of energy use as broadly as possible to help identify the real
cause of the problem. This will help avoid spending money tackling the
symptoms. ETSU has developed troubleshooting guidelines for furnaces, listing
common symptoms and potential causes. These are reproduced in Table 4
(FTJ, 1998a).
Table 4: Checklist for Optimising Furnace Efficiency
Problem Check:
鈥?
Low satisfactory operating instructions have been given and are being
temperature of followed;
metal output
鈥? supervision is adequate;
鈥? the temperatures, quantities, sizes, weights and moisture contents of
all materials charged are as specified;
鈥? refractories and insulation are suitable and in good repair;
鈥? burner control settings are correct, fuel calorific value for the burner is
as anticipated, burner fuel-flow is correct and combustion air flow is
satisfactory;
鈥? electric heating controls are properly set and functioning.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥?
Low metal output temperatures are not unnecessarily high;
output rate 鈥? form, temperature, moisture content and rate of charging of input
materials are as specified;
鈥? materials handling into and out of the furnace are carried out speedily;
鈥? lining or insulation damage is not resulting in excessive heat loss;
鈥? fuel and air flows to burners are properly controlled;
鈥? oxygen flow rates are as specified;
鈥? doors are not over-sized or left open for excessive lengths of time;
鈥? exhaust rates are not excessive.
鈥?
Unsatisfactory composition, proportions in the charge, size, cleanliness and moisture
composition of content of all input materials;
metal output 鈥? order of charging;
鈥? rate of heating;
鈥? temperatures and times of holding;
鈥? composition of the furnace atmosphere.
鈥?
Low yields (in inputs and outputs are weighed;
metal melting 鈥? the charge is as specified in respect of amounts, form, size,
furnace) cleanliness and moisture of all charging materials;
鈥? highly oxidising conditions do not exist;
鈥? excessive superheating temperatures are not employed;
鈥? good separation of slag and metal occurs;
鈥? excessive turbulence does not occur in induction furnaces.
鈥?
High energy electricity tariffs suitable for present operations;
costs 鈥? competitive prices for fossil fuels;
鈥? furnace management 鈥? including output temperatures specified and
achieved, scheduling of inputs and outputs, holding times at high
temperatures, doors open periods, amounts of furnace 鈥榝urniture鈥? used;
鈥? door sizes for loading, unloading and slag removal;
鈥? refractories and insulation, for damage, loss or deterioration;
鈥? burner controls, settings, air:fuel ratios;
鈥? oxygen flow rates;
鈥? the economic case for the use of a waste heat recovery system 鈥? e.g.
involving recuperative or regenerative burners, simple stock drying or
preheating by exhaust gases.
鈥?
High input current inputs 鈥? materials, costs, proportions in the charge, yields
material costs obtained, technical considerations;
鈥? possible alternatives 鈥? costs, proportions necessary, yields
anticipated, possible new technical or quality problems or additional
costs likely to be incurred elsewhere in the process.
鈥?
High labour personnel 鈥? numbers, division of labour, versatility, number of
costs furnaces served, shift patterns, pay rates, supervision;
鈥? input materials 鈥? types, forms, methods of delivery;
鈥? operations 鈥? scheduling, loading, unloading, handling within the
furnace where necessary, control methods.
Source: FTJ (1998a)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Direct energy reduction measures that have had a proven payback include the
following (Environment Canada (1997); USEPA (1992) and FTJ (1997b)):
鈥? Switching off unnecessary cooling fans and other ancillary equipment
If tools and ancillary equipment are routinely left running when not in use,
this could, over time, be adding up to a significant period of non-productive
running time. One option to reduce this may be to run a 鈥榮witch-off鈥?
campaign to raise awareness among staff about the need to turn off
equipment. It may also be possible to automate the switch-off process.
Interlocking control circuits may be able to be installed to automatically
switch off ancillary equipment such as fans, pumps and conveyors when the
equipment they serve is not in use (FTJ, 1998b). It may also be possible to
reprogram major equipment to power-down or switch off during known
breaks or after a time delay.
鈥? Installation of energy efficient lighting systems
Modern lighting systems can reduce running costs by as much as 25%
while achieving the same light output and extended lamp life. There is a
wide range of commercially available lights to suit a range of conditions (i.e.
internal and external lighting). 鈥業ntelligent鈥? control systems can be installed
to alter light output to adapt to ambient light conditions and production
schedules. Even keeping light globes and reflectors free of dust can
increase their efficiency; dirt on lights can reduce the light that reaches the
workspace by 20% (FTJ, 1998b).
鈥? Improve ladle heating technology
Many foundries use inefficient preheating practices such as using gas
torches. Efficient ladle preheating systems are available that can
dramatically reduce energy use (see Example 14) and simple modifications
such as installing lids or turning ladles upside down have been show to
increase energy efficiency in this area.
鈥? Installation of variable speed drives (e.g. ventilation fans, baghouse
extractors etc.)
Specifying the high-efficiency option when replacing motors could reduce
the ongoing running costs by 3鈥?5%.
鈥? Changing technology
Furnace technology is constantly improving to become more energy
efficient, to burn more cleanly and to produce lower environmental impacts.
Regenerative systems that utilise waste heat are becoming more common
and increasingly available for smaller foundries (FTJ, 1999b). Regenerative
furnaces that use natural gas have been shown to reduce energy costs by
between 30% and 50% compared with electric systems. These system
recover around 90% of the waste heat, so that a furnace with an operating
temperature of 1200oC would produce flue gas with a temperature of only
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
100o鈥?100oC. This also helps improve the quality of the working
environment (FTJ, 1999c).
Many foundry furnaces are less than 35% energy efficient. The efficiency of
reverberatory furnaces or crucible furnaces may be improved by upgrading
the combustion system, which also reduces stack emissions. The efficiency
of cupola furnaces can be increased by elevating the oxygen levels in the
air feed. Induction furnaces are about 75鈥?80% energy efficient. They emit
about 75% less dust and fumes than electric arc or cupola furnaces
because of the absence of combustion gases or excessive metal
temperatures. If relatively clean scrap metal is used, the environmental
controls can be greatly minimised.
Upgrading furnaces is clearly an expensive exercise, but it is an area that
can significantly increase the cost effectiveness of the operation. Most of
the foundries in Queensland have converted from cupola furnaces to
electric furnaces in the past decade (see Example 15).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 14: Energy Savings from Electric Ladle
Preheating
Kaye (Presteigne) Ltd., an aluminium diecaster in the UK that melts
around 6000 tonnes of metal each year, installed a 18 kW electric radiant
ladle heater. Prior to this the company preheated its ladles using a hand-
held gas torch that was dropped into the ladle. This created significant
quantities of waste heat and generated fumes, which was an OH&S issue.
The naked flame also created aluminium oxide on the lining of the ladle
which impacted on product quality.
The new system cost 拢6,000 (A$15,000). The system included an
insulated cover that lowered over the ladle to increase heat transfer
efficiency. Energy costs were reduced by 拢4,860 (A$12,150) annually.
This change allowed for a new style of ladle to be used which had better
insulation properties. The company also experimented with new types of
refractory linings. One was identified that had more uniform heat transfer
and a prolonged life 鈥? 18 months instead of the previous 6 months 鈥?
saving an additional 拢1,166 (A$2,900) annually. These changes were
estimated to pay for themselves in around 13 months.
The new system means that the ladle only needs to be preheated at the
beginning of the week rather than at the beginning of each day, which will
generate additional energy savings. Safety is improved due to the
absence of the naked flame and the fact that the ladle is exposed only
during metal transportation. The working environment has been improved
by the reduction of odour and waste heat. Due to the success of the
project, the company is considering installing a second unit.
Source: FTJ (1996a)
A future trend in the foundry industry that will improve energy efficiency will be
the move towards immediate melting and pouring of metal. The aim will be to
reduce holding times as much as possible, with a view to eliminating metal
holding altogether (The Foundryman, 1997a). There is an opportunity for the
industry to develop processes that enable in-situ melting and pouring (like
plastics moulding) to improve metal integrity, and overcome problems with
metal cleanliness and quality associated with conveying and pouring
processes.
Energy reductions can also be achieved indirectly by optimising other
processes such as metal yield and sand yield through;
鈥? improved mould and casting design and casting simulation technology (see
section 3.1.6);
鈥? precision pouring and increased product quality (see section 3.1.8);
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鈥? optimising sand use (see section 5.3).
Some semi-solid casting techniques (see Part 5) have been shown to
significantly reduce energy requirements. These systems heat the metal only
enough to achieve the semi-solid state, rather than the super-heating that takes
place in conventional casting applications.
Example 15: Converting from Cupola to Electric
Furnaces
Most of Queensland鈥檚 major foundries have replaced their cupola
furnaces with electric furnaces over the past decade. In 1997, Bundaberg
Metal Industries, a Queensland foundry, upgraded from a cupola furnace
to an electric induction furnace. The foundry is relatively small, melting
around 650鈥?700 tonnes of metal per year, comprising ductile and grey
iron and some gunmetal. This change has reduced costs and led to a
number of benefits.
Using a cupola furnace meant the company melted around 15鈥?16 tonnes
of metal every four days. A large number of castings would be prepared
over a 3-day period, to be poured on the fourth. This batch process
required significant space for storing moulds in process, and the time
required for fettling would hold up production of the next batch of moulds.
Melting can now be done daily, with around 3鈥?4 tonnes of metal melted in
a day. This change has allowed the company to develop a more
continuous process, with product moving through the facility. The large
stockpiles of coke and lime have also been eliminated, further increasing
space availability. Production capacity has increased and improvements
in emissions and the quality of the working environment have also been
noted.
Source: Spokespersons from Bundaberg Metal Industries
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5. Minimising Foundry By-Products
Key Points
Most conventional foundries generate significant quantities of by-products from
the casting process. These include sand, dusts, slags, refractories, and general
foundry and office wastes. Beneficial reuse is currently an important issue in
Queensland and can help to reduce the cost of managing many of the major
by-product streams. Cleaner Production is different from beneficial reuse as it
seeks to stop the material being generated in the first place leading to greater
cost savings. As well as reducing the cost of disposal, savings can also be
made by reducing the need to purchase new materials, by reducing
unnecessary processing of materials and handling of by-products and by
reducing compliance and environmental control costs.
Some of the key questions to ask in relation to foundry by-products include:
鈥? Have we calculated the full cost of by-products to the company (including
purchasing, processing, disposing and compliance costs)?
鈥? Do we effectively segregate our by-product streams to improve internal and
external reuse options and reduce the cost of disposal?
鈥? Do we have an effective strategy in place to minimise each major waste
stream?
鈥? Can we improve the casting design process to minimise sand use (e.g.
better flask utilisation)?
鈥? Are there other areas of the operation we can improve to minimise sand
waste (e.g. minimise spills)?
鈥? Can we implement computer aided sand mixing systems to minimise sand
and binder use?
鈥? Do we regularly investigate and trial new binder systems?
鈥? Can we improve the efficiency of our sand reclamation system?
鈥? Can we minimise other foundry by-products or reduce the demand for
consumables?
鈥? Once by-products have been minimised as much as possible, are there any
beneficial reuse options that minimise the cost of managing the material?
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All foundries generate by-products from their processes. In Queensland, only a
few foundries segregate their by-products to any great extent. Most foundries
still tend to mix their foundry waste streams (i.e. sand, baghouse dust and slag)
and send them to landfill. Segregation in general waste streams is more
common, with some companies separating recyclable material such as paper,
cardboard and steel drums. Because most companies do not segregate their
foundry by-products, this means that the volume of each needs to be
estimated.
Sand is still the most significant by-product generated, accounting for around
65% of the total volume of materials generated. Baghouse dust probably
accounts for up to 15% of the total, although the amount that is currently
recorded separately in Queensland is around 7%. Dust generation is
increasing as more companies undertake greater sand reclamation and
implement stricter environmental controls. Slag accounts for an additional 5-
10% and other materials such as refractories and general waste account for the
remaining 10-12%.
Figure 4: Breakdown of By-Product Streams in a
Typical Queensland Ferrous Foundry
Slag
Other
8.0%
12.0%
Baghouse Dust
15.0%
Sand
65.0%
In the face of rising disposal costs, many foundries have started investigating
beneficial reuse strategies to reduce costs. While beneficial reuse can reduce
some costs, more substantial savings can be made by stopping waste at
source.
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5.1 Segregation
Segregation is the key to successful management of foundry by-products. For
example, achieving maximum internal reuse of sand requires systems that
minimise contamination. Contamination of sand by excess metal fines,
shotblast or even chemical binders can limit the potential for reuse.
Even in situations where internal reuse is not practicable, segregation can help
open up opportunities for beneficial reuse to reduce the cost of waste disposal.
A large volume of non-hazardous waste contaminated by a small volume of
hazardous waste becomes a large volume of expensive hazardous waste.
Shotblast dust contamination, for example, is often responsible for sand being
classified as hazardous (Environment Canada, 1997).
Some options for improving segregation at foundries include:
鈥? installing dedicated baghouses for the different dust generating processes
(e.g. shotblast dust, furnace dust and sand dust) to segregate potentially
contaminating material;
鈥? installing magnetic separators on baghouses, reclamation units and other
transport systems to remove ferrous metals. This improves the reuse
options for both the sand and the metal fines;
鈥? investing in technologies that have built-in segregation (e.g. shotblast
machines - see Example 16);
鈥? keeping sand from the core sand knock-out area separate from the other
sand streams;
鈥? establishing a separate collection system for resin-containing sands that are
wasted before firing, to avoid high levels of binders contaminating the main
sand stream;
鈥? providing separate bins and bays to collect different by-product streams,
including general waste (see Example 17);
鈥? providing incentives to staff for maintaining good segregation practices (e.g.
casket tickets, bonuses etc. - see Example 18)
Example 16: Self-segregating Shotblast Units
RMC, a Brisbane-based foundry, has replaced its shotblast units with two
new systems that segregate the shot, sand, dust and gunmetal into four
separate streams. This allows the shot to be recirculated and the
gunmetal to be returned to the furnace. Now that shot contamination has
been removed from this sand stream, the company is able to reclaim
100% of its sand. It is estimated that there will be less than 5% loss of
material to the baghouse and other areas.
Source: Spokesperson from RMC
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Example 17: Segregation reduces the cost of general
waste
Ashley Forge, Foundry Division, in the UK, implemented a simple waste
segregation program for solid waste. While minor in terms of total
operating costs, managing solid waste can lead to significant savings
through little additional effort. The change at Ashley Forge was brought
about by a 50% increasing in landfill costs. Waste segregation involved
separating solid and swarfe waste. Timber pallets and other recyclable
materials are separated for return to the supplier or to recyclers. The
immediate savings have been 拢1,750 (A$4,380) per year. Additional costs
of segregation are minimal.
Source: WMC (1999)
Example 18: Achieving Segregation
The Toowoomba Foundry, in Queensland, has realised that there are
many benefits to be gained by segregating its by-products. Up until two
years ago, most waste materials were simply dumped in bulk bins or bays
and periodically disposed to landfill. The company now has separate bins
for most of its by-product streams and is looking at cost-effective
opportunities to increase segregation further. Now easily recyclable
material such as paper, cardboard and metal drums are also kept
separate and reused.
By avoiding contamination of the foundry sand, the company has been
able to send the material to a local compost operator, achieving one of the
first examples of beneficial reuse in Queensland. While the company still
incurs some costs for segregating and screening the material, the overall
costs to the company have been significantly reduced. Segregation of the
baghouse dust has led to the development of a value-added product. The
dust is sintered into a small bead that appears to have excellent water
filtering properties. This product is currently being trialled for a range of
applications.
To help achieve and maintain its segregation goals, the company has
implemented a simple incentive program. If the production teams meet
their segregation targets for a given period the group raffles a gift
voucher. Other incentive programs used in the company include BBQs
and dinners. The program more than pays for itself and is funded using a
portion of the money that is made or saved from the segregation of
recyclable material which is either sold or taken away at no costs (e.g.
scrap steel, cardboard, drums, swarf etc). Some of the service providers
also contribute to the prize pool.
Source: Spokesperson from Toowoomba Foundry
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5.2 Beneficial Reuse
鈥楤eneficial reuse鈥? is a term that is being used by a number of industries to refer
to the use of a by-product generated in one operation in another process. This
is an area that is receiving considerable interest in the Queensland foundry
industry. The Australian Industries Group and the Queensland Environmental
Protection Agency recently formed a beneficial reuse working party to produce
an Environmental Guideline titled Beneficial Reuse of Ferrous Foundry By-
products. A copy of this guideline is provided in the back of this manual as a
summary of the potential for beneficial reuse in Queensland.
Companies are interested in exploring beneficial reuse opportunities due to a
number of perceived benefits. These include reduced waste disposal costs,
improved environmental performance and the potential for reduced liability.
Beneficial reuse is also attractive to some foundries because it can be
implemented without any impact on upstream foundry processes.
While beneficial reuse can play a role in the overall management of foundry by-
products (see Example 19), this manual focuses on options that help foundry
operations reduce waste at source. Beneficial reuse is an end-of-pipe strategy
that does nothing to reduce the cost of producing the by-product in the first
place. It is not, therefore, considered in detail in this manual.
As well as the cost of generating the by-product, beneficial reuse typically
involves costs to the company. The company has to undertake some level of
value-adding including segregation, screening and grading, and also make
some guarantees in regard to the consistency of supply 鈥? both quality and
quantity. Another concern about beneficial reuse is the potential continued
environmental liability for the generator.
Example 19: Beneficial Reuse
Since late 1993, Viking Pump, Inc., of Cedar Falls, Iowa has been
shipping spent sand to a Portland cement manufacturer for use as a raw
material. This reduces the costs for the cement company, since it reduces
the need for virgin sand. Landfill costs for the foundry have been reduced,
creating a win鈥搘in situation for both companies.
When Viking piloted the use of foundry sand in cement manufacturing, the
sand was loaded with an endloader into grain trucks and hauled to the
cement plant. Once the cement company decided that the waste sand was
compatible with its process, Viking invested in a sand silo for storage. The
sand is now conveyed to the silo and gravity fed into trucks. This reduced
handling time from around an hour to 6 minutes. Viking expects to send at
least half of its spent foundry sand to the cement manufacturer and is
continuing to look for alternative uses and greater utilisation.
Source: USEPA (1992)
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Despite the challenges, beneficial reuse can and will play an important role in
minimising foundry wastes in Queensland. Experience in other countries
indicates that many of these options are becoming a reality. Early experience in
Queensland is proving to be fairly positive but a number of issues need to
addressed. Some of the major beneficial reuse options are listed in Table 5.
Table 5: Beneficial Reuse Options for Foundry By-
products
Greensand Resin shell sand
鈥? flowable fill / aerated concrete 鈥? flowable fill / aerated concrete
鈥? cement manufacture 鈥? cement manufacture
鈥? brick / asphalt manufacture 鈥? brick / block manufacture
鈥? land-fill liner / cover 鈥? road / asphalt construction
鈥? construction fill 鈥? soil improver
鈥? soil improver 鈥? smelting flux
鈥? waste vitrification (stabilising hazardous
Alkaline phenolic sand
鈥? smelting flux waste)
鈥? waste vitrification (stabilising hazardous Investment casting shell
鈥? coarse aggregate substitute
waste)
鈥? flowable fill / aerated concrete 鈥? absorbent media
鈥? cement manufacture Desulfurisation slag
鈥? slaked lime replacement
鈥? brick / asphalt manufacture
鈥? soil modification
鈥? road construction
鈥? blast furnace cement
鈥? soil improver
Water quenched cupola slag
Dust and sludges
鈥? blockmaking
鈥? fertiliser fillers
鈥? abrasives
鈥? chemical and industrial applications
鈥? soil modifiers
鈥? soil modifiers
鈥? landfill lining / capping Induction melting slag
鈥? road base construction
鈥? artificial topsoil
鈥? abrasives
鈥? lightweight aggregate production
Electric arc furnace slag
Sodium silicate sand
鈥? road base construction
鈥? Cement / mortar production
鈥? ballast
鈥? insulating wool manufacture
鈥? waste vitrification Air-cooled cupola slag
鈥? Course aggregate substitute
鈥? road base construction
鈥? road base construction
Furane sand
鈥? decorative ground farms
鈥? roofing felt
鈥? brickmaking
鈥? insulating wool
鈥? insulating wool
鈥? brick and blockmaking
鈥? asphalt
鈥? soil products (mixed with greensand)
鈥? ballast
Sources: BUIC (1999) and EPA (1999)
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5.3 Optimising Sand and Binder Use
Improving sand yields, by minimising the amount used in the operation and
through reclamation practices, not only reduces disposal costs but also
reduces purchasing and production costs (e.g. new sand and sand handling).
Binders and catalysts are added to the sand to achieve sufficient hardness of
the mould and, more importantly, cores. Chemical binders typically account for
around 1鈥?3% of the sand mix by weight. In terms of the total cost, however,
binder can account for as much as 30鈥?60% (FTJ, 1998i). A focus on volume
rather than on cost, when identifying opportunities for improvement, can lead
some foundries to disregard binders. However they can be an important source
of savings.
5.3.1 Minimising Sand Use
Foundries can minimise the use of mixed sand in a number of ways. These
include:
鈥? improving cast design by adding more units to each box can improve the
sand:metal ratio;
鈥? using a range of flask sizes so that each casting is done in the most
appropriate flask;
鈥? inserting blocks or other material to fill voids in the flask so as to limit the
need to use sand;
鈥? using new sand for the sand/metal interface only and backfilling with non-
reclaimed, non-mixed sand;
鈥? minimising spillage as much as possible (Using bobcats to move sand, for
example, is a major source of sand loss.);
鈥? optimising the sand mixing system (see below).
Control of sand mixing (see Example 20) is an area where companies can
achieve a number of benefits. As well as optimising the amount of binders and
catalysts used, process control can increase the predictability of mould and
core quality and set times. A problem experienced by foundries using chemical
binder systems is the variability of sand temperatures, which affects the amount
of resin and catalyst needed to achieve the desired quality and the time
required for effective catalyst activation (FTJ, 1996m). This in turn can lead to
downstream quality problems and higher than necessary emissions.
One Queensland company is investigating a simple process control system in
its core shop. Temperature probes in the sand/binder mixer can be used to
control a variable rate dispenser system for two catalysts, one a rapid ester
catalyst and the other a slow ester catalyst. By varying the proportion of each
of these catalysts, the system could achieve a constant set time regardless of
sand and ambient temperatures. This would help achieve a more consistent
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core quality. This would also allow the throughput to be more streamlined,
allowing better integration with upstream and downstream processes.
Example 20: Computer-aided Sand Control Systems
Beijing Jeep, a greensand foundry in China which produces 6000 tonnes
of castings annually, reduced its reject rate due to sand quality problems
by 46%. This was achieved by incorporating an online sand testing and
intelligent control system on the sand mixer. Prior to the change, sand-
related scrap was 4.8% of total product sold. Within 2 years, this was
reduced to 3%. The sand control system also reduced the demand for
inputs, most notably bentonite which was reduced by 378 tonnes per year.
This represents a reduction of 63 tonnes of bentonite per 1000 tonnes of
castings.
The online sampling system tests sand compactability and strength, then
automatically controls addition of water which is the key variable for
finetuning sand quality. Each batch requires one or two test cycles and
water additions and, with total cycle times being less than 2 minutes, the
system is suitable even for intensive mixers.
Prior to the implementation of the control system, compactability
fluctuated widely from 22% to 50%. Improved control reduced the
fluctuation to between 37% and 43%.
Source: FTJ (1998j)
5.3.2 Optimising Binder Use
Most companies seek to reduce the cost and environmental impact of binders
by investigating alternative binders and by trying to optimise binder use.
Methods that help minimise binder use include:
鈥? minimising the use of mixed sand by improving the sand:metal ratio;
鈥? minimising the loss of mixed, un-cast sand. Sand can be reclaimed but
binders cannot. During the pouring stage, most binder is burned off the
sand. Unfired sand contains higher levels of binder and thus creates
additional environmental problems;
鈥? mixing only the quantity of sand that is needed;
鈥? increasing operator awareness about the need to minimise sand loss;
鈥? monitoring binder levels in reclaimed sand so that less new binder is added;
鈥? ensuring reclaimed sand has cooled prior to reuse to minimise binder burn-
off during mixing;
鈥? setting optimum binder levels;
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鈥? calibrating and maintaining mixing equipment carefully to achieve consistent
binder levels;
鈥? maintaining good inventory practices to avoid stock going out of date and to
avoid stock damage or spillage;
鈥? continually monitoring the development of new binders and undertaking
trials to determine their potential benefits to the operation (FTJ, 1999d).
Binder performance is continually being improved (see Example 21).
Increasingly, chemical companies are offering improved binder systems that
reduce cost and environmental impact while maintaining or improving product
quality and production rates. Companies should have a program to identify new
binder systems and trial them on an ongoing basis (see Example 22).
The elimination of binders altogether is a significant benefit that can be
achieved by changing part of all of the production system to an alternative
casting process, such as the lost foam process or vacuum moulding systems
(see Part 5).
Chemical binders typically have a limited usable life once they are prepared.
After pouring, the heat from the metal burns off most of the resin, leaving only
low levels of resin in the sand. Resin-coated sand that is wasted before firing
can, however, have higher levels of resin and these can build up over time in
recirculating systems. Further, in liquid form, many resins are classified as
hazardous waste so must be treated with care. Waste resins have to be cured
prior to disposal, which can lead to significant costs in terms of catalyst addition
and labour to handle the material (FTJ, 1997h). This highlights the importance
of effective storage and stock control to minimise waste in this area.
Regular monitoring and control of process variables, such as binder additions/
catalyst levels, reclaim to new sand ratio, loss on ignition, fines and dust loss,
should be maintained to keep binder use to a optimum level (FTJ, 1997h).
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Example 21: Reducing Binder Inputs
Rayne Foundry in Essex, UK, is a ferrous and non-ferrous jobbing foundry
that uses furane no-bake binders. In the early 1990s, the company used a
Supaset鈩? 53 system, which required the addition of a phosphoric xylene
sulfonic acid catalyst at a rate of 44% of resin volume. Resin consumption
was around 1.3% of sand volume.
The major environmental concern from this binder system was the
generation of SO2 emissions. To address this problem the company
investigated alternative systems. In 1994, the company introduced the
Pemacol鈩? system with a binder content reduced to 0.85% and also a
reduced acid content, which resulted in a 50% reduction in emissions from
the casting area.
The company then identified an opportunity to better control catalyst
addition by installing a temperature-sensitive acid blending unit. This
control helped ensure that the 50% reduction was maintained over the
year regardless of temperature. The mixed sand costs were significantly
reduced and phosphate was eliminated from the sand, allowing reclaimed
sand to be used in the non-ferrous casting line. This increased on-site
sand reclamation from 80% to 94%.
Hadleigh Castings in Suffolk had a similar experience. Prior to 1994, the
company was using an alkaline phenolic binder system. Through a range
of improvement programs they were able to reduce resin levels to
between 1.4% and 2%, depending on the base sand used. The company
installed a mechanical reclamation process to reduce the cost of sand,
however they found that, due to the nature of the binder system, the core
and mould strength of the reclaimed sand was lower than for new sand.
Since the company鈥檚 customers were increasingly demanding higher
dimensional accuracy, the company had to purchase high-grade sand at
significant expense and had to increase binder levels for reclaimed sand.
The company decided that it would be difficult and expensive to achieve
further benefits from the current sand system, so they decided to change
to a furane sand system. This helped the company achieve a number of
improvements, including:
鈥? a reduction in binder levels to 0.7鈥?0.8%;
鈥? increased sand reclamation to around 85%;
鈥? greater dimensional accuracy; and
鈥? a reduction in scrap from mismatch caused by the plastic nature of
phenolic binders.
The company has more recently changed to the Permacol鈩? sulfur-free
furane binder system to greatly reduce SO2 emissions.
Sources: FTJ (1996d) and The Foundryman (1997c)
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Example 22: Reducing Binder Inputs in Queensland
In an effort to reduce odour from the site, AustCast Australia, in Brisbane,
implemented several improvements to reduce the amount of binder being
used in the moulding process. The company changed their sand supply to
reduce the shell and fines content, which allowed them to reduce binder
inputs. By improving the binder:sand ratio and the sand:metal ratio, they
reduced binder use by 0.6% (a saving of 96 tonnes of resin per year).
This significantly reduced the cost of binders to the company.
Source: Spokesperson from AustCast Australia
5.3.3 Sand reclamation
Reclamation of sand can be undertaken using a number of techniques. Most
pertinent for Queensland are mechanical reclamation, which is commonly
practised in the State, and thermal reclamation, which has been undertaken by
one company and is being investigated by several more. Note that internal
sand reclamation is considered under a different heading to beneficial reuse
which refers to reuse of by-products outside the foundry industry.
Many of the larger foundries in Queensland currently undertake manual sand
reclamation. The reclamation rate is typically limited by two factors: the ability
to cool the sand quickly enough and the quality requirements of the sand that
dictated the ratio of new to reclaimed sand. The highest rate of manual
reclamation is achieved by Bundaberg foundry (96%) and Walkers (90%). This
is due to the fact that they produce large iron castings and quality can be
achieved with a relatively small sand grain size. Therefore, losses from the
system are predominantly spills and baghouse dust (typically less than 5%).
For most operations, manual reclamation is likely to be limited to around 70鈥?
80%. ANI Bradkin (Runcorn) currently achieves around 70% efficiency;
Austcast currently achieves 30% but plans to increase this rate to around 65鈥?
75% with the installation of a sand cooling system. ANI Bradkin (Ipswich) is
planning to install a mechanical reclamation plant that would be expected to
achieve 70% recovery.
The average rate of sand reclamation across the foundry sites surveyed is
currently 36%. This means that, while the industry buys 48700 tonnes of sand
each year, recycling raises the total weight of sand used in castings in
Queensland to approximately 177000 tonnes per year. Therefore, internal
recycling currently reduces the volume of sand purchased by the industry by
around 131000 tonnes per year.
As discussed, plans to commence or increase reclamation are being
considered by ANI Bradkin (Ipswich) and Austcast. RMC plan achieve close to
100% reclamation by the end of 1999. If these three projects were
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implemented, this would increase the industry average internal recycling rate to
50%. Assuming no change in production, this would reduce spent sand
generation by around 30% or 14200 tonnes per year.
Moving beyond this average internal recycling rate of 50% will be relatively
difficult. A further 5% may be fairly easily gained if companies work to improve
the efficiency of the current systems. Further gains will then need to come from
shifting to thermal or other reclamation processes, by improving moulding
techniques to reduce the sand:metal ratio, by changing the sand/resin systems
and casting processes used, or by identifying cost-effective methods to reclaim
sands at small foundries.
Sand reclamation plays an important role in the overall Cleaner Production
strategy for the industry. Its use should be considered in conjunction with other
components such as beneficial reuse and process improvements. A
hypothetical Case Study is presented on the following pages (see Example 23).
This discussion is intended to show how a typical Queensland foundry may
integrate different approaches to minimise the cost and environmental impact
of sand for the company.
Example 23: Sand Optimisation - A Hypothetical Case
Study
MetalCast Ltd is a hypothetical company that will be used as an example to
demonstrate some of the concepts of Cleaner Production. Sand is one of the
largest waste issues in the foundry industry, so this will be used as the focus of
the example. The data used are indicative of typical volumes and costs for
foundries operating in south-east Queensland, but do not specifically represent
the costs or activities of any particular foundry.
Initial Situation
MetalCast Ltd is a medium-sized foundry operating in the Brisbane area. The
company produces 3000 tonnes of ferrous castings annually. The process uses
approximately 3 tonnes of sand for every tonne of product, thus the company
uses 9000 tonnes of sand per year. The company does not reclaim any sand,
so purchases the full 9000 tonnes of virgin sand annually. The baghouse
removes around 5% of the sand as baghouse dust (see Figure 5).
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Figure 5: Initial Situation
Total sand used: 9000 tpa
Core shop
1800 tpa (20%) Spent sand (95%)
New sand (100%)
8550 tpa
9000 tpa
Mould Shop
7200 tpa (80%)
Recycle rate: 0% Landfill
Baghouse dust (5%)
450 tpa
The company pays $25 per tonne for new sand (including transport) and $20
per tonne for disposal of both spent sand and baghouse dust. The total costs
for this situation are shown in the Table 6
Table 6: Annual Costs Prior to Improvements
Tonnes/year Cost/tonne Cost/year
Total sand used 9,000
Total sand in 9,000 $25 $225,000
Total sand out 8,550 $20 $171,000
Total baghouse dust (5%) 450 $20 $9,000
Total cost: $405,000
From this table it can be seen that the total cost of sand to the company is
$405,000 per year.
Project 1: Beneficial Reuse
The company realised that the cost of its spent sand could be reduced if it
could identify a beneficial reuse for the material outside the operation. This
would save the company money and help the environment by stopping sand
going to landfill. The company investigated a range of options and identified a
cement manufacturer that was interested in taking the material. The company
had to screen the material, to ensure it met the specification of the company,
and pay part of the transport costs. The new situation is shown in Figure 6.
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Figure 6: Situation After Beneficial Reuse
Total sand used: 9000 tpa
Core shop
1800 tpa (20%) Spent sand (95%)
New sand (100%)
8550 tpa
9000 tpa
Mould Shop
7200 tpa (80%)
Recycle rate: 0% Beneficial
Reuse
Baghouse dust (5%)
450 tpa
The total cost of these operations was $10 per tonne: half the disposal costs.
The total costs after beneficial reuse are shown in the Table 7.
Table 7: Annual Costs After Beneficial Reuse
Tonnes/year Cost/tonne Cost/year
Total sand used 9,000
Total sand in 9,000 $25 $225,000
Total sand out 8,550 $10 $85,500
Total baghouse dust (5%) 450 $20 $9,000
Total cost: $319,500
The total cost savings of this change were $85,000 per year.
Project 2: Mechanical Sand Reclamation
The company realised that, while they were now saving a significant proportion
of their disposal costs, they still had to pay for the sand in the first place.
Unless a better beneficial reuse option could be found, the cost of managing
the by-product was still quitehigh.
The company decided to investigate options for internal reuse. The company
identified a suitable mechanical sand reclamation system that could achieve a
70% reclamation rate. This rate was limited by the fact that new sand had to be
used for the production of cores and to compensate for losses from the system
such as baghouse dust and general spills. A second baghouse was installed on
the reclamation unit and total dust generation was increased to around 8% of
total sand processed annually. The new situation is shown in Figure 7.
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Figure 7: Situation After Mechanical Sand Reclamation
Total sand used: 9000 tpa
Core shop
1800 tpa
New sand (30%) 1,800 tpa (20%) Spent sand (22%)
Mechanical
2700 tpa 1980 tpa
reclamation
900 tpa
Mould shop
6300 tpa
7200 tpa (80%)
(70%)
Beneficial reuse
Recycle rate: 70%
Baghouse Dust (8%)
720 tpa
The 70% reclamation rate reduced the volume of sand purchased to 2700
tonnes per year; 9000 tonnes was processed through the reclamation unit
annually to maintain the rate of production. The volume of spent sand going to
beneficial reuse was reduced to 1980 tonnes per year. The total sand costs to
the company after it commenced mechanical reclamation are shown in Table 8.
Table 8: After Mechanical Sand Reclamation
Tonnes/year Cost/tonne Cost/year
Total sand used 9,000
Total sand in 2,700 $25 $67,500
Total sand out 1,980 $10 $19,800
Total baghouse dust (8%) 720 $20 $14,400
Total cost: $101,700
The cost savings generated by this improvement were $217,800, bringing total
savings up to $303,300 per year. The capital cost of the reclamation unit was,
conservatively, $200,000. Operating costs were around $12 per tonne or
$108,000 per year. Net annual benefits were therefore $109,800. This meant
that the expected payback for the equipment was 1.82 years.
Project 3: Process Improvement
The improvements as described significantly reduced the cost of sand disposal
and the cost of purchasing new sand. The company realised that the next
challenge was to reduce the cost of unnecessarily processing sand. The
company suspected that its sand: metal ratio, 3 tonnes of sand for every tonne
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of product made, was fairly high. The company believed that through process
improvement they could reduce the total amount of sand needed in the
process. This would further reduce the cost of sand purchase and disposal. It
would also reduce the cost of mechanical reclamation and other activities such
as sand mixing and handling.
The company investigated the process and identified a number of issues that
increased the volume of sand use.
Problem Solution
a) The sand mixer produced more sand a) Better process control on the mixer to
than was needed in each shift. This sand reduce waste.
had to be wasted.
b) New sand was used to fill the entire b) For larger castings, new sand was used
mould when a large proportion of the for the sand/metal interface and the
sand did not have contact with the metal. mould was then backfilled with spent,
non-reclaimed sand. Concrete blocks
were used to fill larger voids in the mould
cavity.
c) Small castings took up only a very small c) The company implemented a second
proportion of the mould. smaller mould box size that was used for
smaller castings.
d) Small amounts of sand were spilled d) A general Cleaner Production awareness
throughout the process, particularly at program was developed which helped
the sand mixer. improve general housekeeping, resulting
in less sand waste.
These changes reduced the sand:metal ratio by around 17%, from 3:1 to 2.5:1.
This reduced the total amount of sand needed from 9000 tonnes to 7500
tonnes per year. This situation is shown in Figure 8.
Figure 8: Situation After Process Improvement
Total sand used: 7500 tpa
Core shop
1500 tpa
New sand (30%) 1500 tpa (20%) Spent sand (22%)
Mechanical
2250 tpa 1650 tpa
reclamation
750 tpa
Mould shop
5250 tpa
6000 tpa (80%)
(70%)
Beneficial reuse
Recycle rate: 70%
Baghouse Dust (8%)
600 tpa
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The total costs for this situation are shown in Table 9.
Table 9: After Process Improvement
Tonnes/year Cost/tonne Cost/year
Total sand used 7,500
Total sand in 2,250 $25 $56,250
Total sand out 1,650 $10 $16,500
Total baghouse dust (8%) 600 $20 $12,000
Total cost: $84,750
The cost savings generated by this improvement were $16,950, giving total
savings of $320,250 per year.
Project 4: Core Sand Reclamation
The next major improvement the company wanted to tackle was to reclaim the
remaining waste sand for use in the core shop. Around 20% of the sand 鈥?
1500 tonnes per year 鈥? was used in the core shop. Technically, a thermal
reclamation unit could further process a portion of the mechanically reclaimed
sand, which would return it to an 鈥榓s new鈥? quality. This would allow the sand to
be used in the core shop and would virtually 鈥榗lose the loop鈥? in terms of sand.
This can be seen in Figure 9.
Figure 9: Situation After Core Sand Reclamation
Total sand used: 7500 tpa
1550 tpa
(21%)
Thermal
Core shop
reclamation
1500 tpa (20%) Spent sand (1%)
New sand (9.3%)
75 tpa
700 tpa Mechanical
Mould shop reclamation
6000 tpa (80%)
5250 tpa
Landfill
(70%)
Recycle rate: 70% + 21% = 91%
Baghouse dust (8.3%)
625 tpa
The high cost of thermal reclamation was known to be high. The company had
priced appropriate systems in the range of $250,000 to $500,000. The thermal
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reclamation unit could be expected to achieve about 95% reclamation of the
sand processes through the system. In total, it would be designed to supply
around 21% of the total sand used in the year. The total recycling rate for both
reclamation units would therefore be around 89%. The new system would
increase total baghouse dust generation to around 8.3% of the sand processed
annually, or 625 tonnes. Only 75 tonnes of waste sand would be generated
each year due to minor spills and other loses. This means that the company
would no longer have sufficient quantity of sand to maintain their beneficial
reuse arrangement. They would, therefore, have to send to landfill at the higher
cost of $20/tonne. The total costs for this situation are shown in Table 10.
Table 10: After Core Sand Reclamation
Tonnes/year Cost/tonne Cost/year
Total sand used 7,500
Total sand in 700 $25 $17,500
Total sand out 75 $20 $1,500
Total baghouse dust (10%) 625 $20 $12,500
Total cost: $31,500
The potential cost savings generated by this improvement would be $70,200,
achieving total annual savings of $373,500 per year.
Operating costs were expected to be less than $15/tonne or $24,750 per year.
Net annual benefits would therefore be $45,450. Given the range of capital
costs, the company could achieve a payback within 5.5鈥?11 years. This
timeframe was considered to be fairly long but, as the cost of new sand and
landfilling were expected to rise significantly, the company felt that the options
would become increasingly viable in the near future.
The Future
The four improvement projects discussed above reduced the company鈥檚 total
sand costs by over 90%. The company summarised these cost improvements
in Figure 10.
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Figure 10: Summary of Cost Improvements at MetalCast Inc.
$450,000
Baghouse dust
$400,000
Sand out
$350,000
Sand in
$300,000
$250,000
$200,000
$150,000
$100,000
$50,000
$0
Initial Situation
Beneficial reuse
improvement
reclamation
reclamation
Mechanical
Thermal
Process
The company identified that the most significant improvements in cost were
achieved when sand use was reduced at source. Beneficial reuse, while
reducing the cost of the by-product management, did nothing to reduce the cost
of generating the by-product in the first place.
By reducing sand at source, such as through reclamation or by improving
process efficiency, the company saved money in a whole range of areas
including:
鈥? reduced input costs (e.g. energy and materials);
鈥? reduced disposal costs;
鈥? reduced processing and handling costs;
鈥? reduced maintenance costs;
鈥? reduced compliance costs.
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Mechanical sand reclamation plants break the lumps down to grain size and
remove resins and contaminants by attrition and dust extraction (see Example
24 and Example 25). The levels of resins and catalysts present in the sand are
reduced during firing and reclamation but they are not entirely eliminated.
Binding level can often be reduced with reclaimed sand. Waterman foundry in
the UK introduced mechanical reclamation and reduced new sand purchases
by 75%. Binder and acid purchases were also reduced by around 35% as a
result of using reclaimed sand (FTJ, 1997f). Reuse can cause binders and
other contaminants to build up over time creating highly acidic or alkaline
conditions, depending on the binder system used (FTJ, 1998i). Paints and
glues used in the process can also present contamination problems.
Example 24: Mechanical Sand Reclamation
The Chicago Faucet Co., a red brass foundry in the United States, uses a
ball mill to recycle the material that is generated from the sand screening
system. All the furnace skims, floor spills, slags, core butts and tramp
metal from the screening are dumped into a vibrator. The vibrator feeds a
rotating ball mill, which pulverises all materials into very small particles.
The material then passes through a vibrating screen and an impactor.
Further, more than 90% metallic material can be returned to the furnace.
Source: USEPA (1992)
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Example 25: Internal Reuse of Foundry Sand
KHD Humboldt Wedag installed a multistage process for regenerating
used foundry sand. This process included iron removal by a magnetic
separator, followed by reclamation in a fluidised-bed furnace consisting of
a vertical, cylindrical brick-lined reaction chamber and a second reaction
chamber to ensure the gases are completely burned
Heat is recovered for use in the foundry by counter-current water flow
through the regenerated sand. The sand is further cleaned of impurities in
a counter-current impact mill consisting of two gas jets, which clean the
particles with application of friction. The system cost 5,480,000 DM (A$4.6
million). The operating costs for the systems regenerating 5 tonnes of
sand per hour was 532,000 DM (A$444,000) per year. The sand disposal
costs were 48 DM (A$40) per tonne.
The system reduced sand disposal by 75鈥?80%. Stack emissions were
also reduced. Heat recovery saved approximately 250,000 DM ($A209),
reducing the operating costs of the recovery system to 282,000 DM
($A236) per year. Savings in disposal costs of approximately $60,000 DM
(A$50,000) per year. Savings in new sand purchases were estimated to
be around 12500 tonnes per year.
Source: ICPIC (1999)
Thermal reclamation is an alternative system that thermally drives off organic
materials including binders (see Example 26 and Example 27). Assuming that
contamination can be kept to a minimum during the casting process and other
handling activities, the quality of reclaimed sand should not be significantly
different from that of new sand (FTJ, 1998i). Thermal reclamation typically
achieves very high rates of reuse: up to 98%. The only wastes generated are
clean dust and air emissions that contain the organic materials burnt off (FTJ,
1998i).
Some companies report that thermally reclaimed sand is in fact of higher
quality than virgin sand, because many of the organics that can be present in
the original sand are removed during pouring and reclamation. Further, the
thermal expansion properties are more predictable in subsequent pourings.
A further potential benefit of thermal reclamation systems is that baghouse
dusts can be treated to render them inert. This can reduce the disposal cost of
this material, particularly for non-ferrous foundries. If this practice is carried out,
care needs to be taken to ensure that contaminants are not introduced into the
sand.
Because of the high rate of recycling achieved in thermal systems, sand quality
and testing become more important. For example, if binders with long strip
times are used, high levels of impurities can neutralise the small amount of
binder used, creating problems with incomplete core hardening (FTJ, 1998i). If
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maximum internal reuse is going to be considered, therefore, it is important to
maximise the quality of the base sand, to minimise contamination and
undertake regular on-the-spot sand testing. These precautions will help
minimise the risk of system failure.
Thermal reclamation is typically considered too expensive for many
Queensland foundries. Depending on the scale of the unit and the ancillary
equipment used, capital costs that would be applicable to Queensland
foundries range from $200,000 to $1 million.
Two potential solutions to this problem are the development of centralised
thermal reclamation processes or smaller mobile units that can be shared
between smaller foundries. This first approach is being developed in
Queensland by a company, Resin Coated Sands, that has established a
thermal reclamation operation at Eagle Farm in Brisbane. This was initially
established to recover shell sand from one company (see Example 27), but the
company plans to extend this service to other foundries. This option may not be
suitable for smaller foundries or those that are located significant distances
from the centralised operation.
An alternative may be to develop a mobile reclamation process that can be
shared between facilities. At present, no mobile units are in operation in
Queensland. In Germany, R+A Recycling and Anlagentechnik GmbH offer a
door-to-door service that can be used to thermally reclaim many types of
foundry sands (FTJ, 1996k).
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Example 26: Overseas Examples of Thermal
Reclamation Systems
Carondelet Foundry Company in Missouri, USA, installed a fluidised bed
thermal sand reclamation unit and a mechanical reclaimer in 1994 to treat
its phenolic urethane no-bake and phenolic urethane Isocure sand. Prior
to this, the steel jobbing shop was disposing of an average of 150 tonnes
per day of waste sand off-site for landfill disposal, at a cost of about
US$29 per cubic yard (A$58 per cubic metre). In addition, new sand was
costing approximately US$22 (A$34) per tonne.
The thermal system processes 125 tonnes per day and the mechanical
system processes the remaining 25 tonnes. Only 5% of the foundry鈥檚 sand
is not reclaimed. The reclamation system is estimated to save the foundry
over US$1 million (A$1.5million) per year and paid for itself in under a
year. In addition, the foundry feels that the reclaimed sand is better than
new sand and results in better castings.
In 1988, R.H. Sheppard Company, Inc. in Pennsylvania installed a thermal
sand reclamation system to recover its 2200 tonnes per year of waste
green sand. The foundry was spending over US$180,000 (A$277,000) per
year on new sand purchases and disposal costs. Even considering the
US$428,500 (A$660,000) capital investment and regular operation and
maintenance costs, over the 20-year useful life of the equipment, the
company estimates it will save about US$2 million (A$3 million). This does
not include the intangible savings of reduced liability for waste sand
disposal.
Triplex Alloys Ltd, Darlaston, UK produces 1500 tonnes per year of
aluminium castings by gravity die-casting (66%) and chemically bonded
boxless sand moulding (33%). The company uses phenolic urethane
binder systems. The company used a mechanical attrition system to
reclaim sand but the binders reduced the internal reuse ratio. The
standard blend of old sand to new sand was 30:70. This led to new sand
purchases of 75 tonnes per week, at a cost of 拢58,000 (A$145,000) per
year and disposal cost of the same volume of 拢24,500 (A$63,750) per
year. The company installed a thermal reclamation system which restored
the sand to an 鈥榓s new鈥? condition. This virtually eliminated the need to
purchase new sand and pay for sand disposal. The system cost 拢48,000
(A$120,000) and the operating costs were 拢3.96 per tonne or 拢13,700
(A$34,250) per year. The total cost saving was 拢68,800 (A$172,000)
year, which achieved a payback of 9 months.
Sources: UNEP (1997) and ICPIC (1999)
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Example 27: Thermal Reclamation Systems In
Queensland
RMC (Reliance Manufacturing Company) was the first Queensland
foundry to undertake thermal reclamation of its waste shell sand. Waste
sand from shell moulds cannot be reclaimed mechanically, so the
company needed to look at thermal methods. The company did not have
sufficient space to undertake the process on-site so they arranged to have
their sand supplied by an innovative company, Resin Coated Sands
(RCS), which was able to offer full reclamation services.
RCS established an operation at Eagle Farm in Brisbane, and
commenced thermal reclamation of RMC鈥檚 sand. For the first 6 months the
operation achieved approximately 40% reclamation. Within the first year,
100% reclamation has been achieved. This required an improvement in
RMC segregation practices to eliminate shot contamination (see Example
16 ). The reclaimed sand is reported to have better properties than new
sand because it contains less organic material and exhibits less thermal
expansion during the pouring process. This, along with beneficial reuse,
should eliminate most of the waste from RMC鈥檚 site.
Resin Coated Sands has indicated that, once the system has been
optimised for RMC, they will increase their production capacity further to
allow them to treat sands from other operations. Several companies have
expressed interest in using this service and initial trial work has been
conducted for some companies. Preliminary results suggest that the cost
of the treated sand will be higher that the cost of new sand, but less than
the total current costs including transport and disposal.
Source: Spokespersons from RMC and Resin Coated Sands
A novel strategy for further improving the cost effectiveness of thermal
reclamation is to combine heat treatment and thermal sand reclamation
processes into one system. Such a system has been developed by
Consolidated Engineering Company under the trade name Sand Lion. While
these systems are currently being implemented by large repetitive foundries,
the principles may be applicable to smaller foundries in the future. In these
systems, the moulds are sent directly from the pouring area to the specially
designed heat treatment oven. Moulds and cores are thermally treated while
being knocked out. The sand is reclaimed and returned via a cooler classifier to
storage silos. Sand from other (i.e. jobbing) areas in the plant can also be
reclaimed through the system.
These systems achieve high levels of energy efficiency, since moulds are
transferred directly to the oven rather than being allowed to cool. The binders
also provide additional fuel value to the process. Space requirements can be
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reduced because it is no longer necessary to maintain separate areas for heat
treatment, knockout and reclamation (FTJ, 1996i).
5.4 Minimising Other By-Product Streams
5.4.1 Optimising other Refractory Material
The choice of refractory material used to line furnaces and ladles can play a
role in the efficiency of the process. More furnace linings fail, however, due to
poor operational practices rather than to poor refractory material (Metal,
1997a). Therefore, the selection of the refractory or combination of materials
should be made after a consideration of the total process. Some of the factors
that should be considered include the following:
鈥? Operating temperature 鈥? the range of temperatures, particularly
temperature excursions have a significant impact on refractory life.
Improved control systems may increase refractory life while achieving
energy and other operational improvements.
鈥? Type of charge 鈥? the refractory should be compatible with the composition
of the melt and the melting point.
鈥? Slag 鈥? the composition of slag is unique for each melt, and the refractory
needs to be selected to sustain chemical attack. Composition, basicity,
turbulence and splash are important consideration when designing
appropriate linings.
鈥? Furnace and ladle design 鈥? the design and location of tap holes, the type
of furnace and ladle used, the types of filters used and the furnace
atmosphere (i.e. oxidising or reducing) all have an impact on refractory
choice and life.
鈥? Melting practices 鈥? superheating practices, holding times and the
duration of non-operational periods are also important considerations
(Metal, 1997a).
Keeping good records of refractory practices, measuring and documenting
lining type and life, and reasons for failures will help build up a profile of major
problems and allow refractory practices to be optimised.
Maximising refractory life can reduce materials and maintenance costs as well
as achieving a number of Cleaner Production benefits. Refractory lining life is
reduced by general wear and through chemical attacks from slags. Slags are
formed during the melting process and contain a range of oxides. The exact
composition depends on the dominant chemicals in the melt, so is unique to
each furnace. A range of refractory materials are available which are designed
to withstand attacks from certain oxides. Selecting the best lining material or
combination of materials may help maximise lining life for a particular furnace.
Additives that prevent oxide formation can be used to reduce slag formation.
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Ladle design, and maintaining the quality of the refractory lining play important
roles in casting quality. The performance of refractory material in ladles may be
overlooked because the ladle is used only to transfer and pour the metal. Poor-
quality or damaged material can significantly increase the levels of inclusions.
Ladle design can also affect the ability to produce a clean cast due to
turbulence and stream velocity (Metal Asia, 1998b).
5.4.2 Optimising Blast Media Use
The selection of blast media can have a commercial impact on product quality,
process throughput and efficiency, media life and recycling opportunities. Shot
suppliers can provide advice as to the best options. Many alternatives exist of
each metal types and new media are continually being developed to help
achieve increased efficiency and reduce waste and dust generation from the
process (FTJ, 1998e).
5.4.3 Minimising General Waste
General waste, such as paper, cardboard and metal drums, can also be
minimised or segregated to reduce costs to the foundry (see Example 28).
Example 28: Reducing the cost of general waste
disposal
West Yorkshire Foundry, UK, halved the cost of general waste disposal
by installing two roto-compactors. Formerly, skips were used to collect
and remove waste at a cost of 拢20,000 (A$50,000) per year.
The compactors help contain the waste better and create a cleaner, more
presentable site. There is also less disruption and hassle from waste
contractors constantly coming on-site to remove skips.
Source: FTJ (1997a)
5.4.4 Reusing Swarf and Baghouse Dust
Bricketting systems are available for swarf and other metal chips. These
systems compact the material, making it easier to handle, and add value to it by
removing a significant proportion of the oil and other moisture (typically up to
95%). This may improve the options for on-site reuse and increase the value of
the material to recycling markets (see Example 29). If material is segregated
appropriately, there is the potential to separate the cutting fluids for direct on-
site reuse, filtering or off-site reprocessing (FTJ, 1999f).
Cupola furnaces have the advantage of being fairly tolerant of oily and
contaminated scrap. They will also scavenge metals from low-grade sources
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such as slag and some baghouse dusts. Most of the major Queensland
foundries have shifted to electric furnaces, which need high-quality scrap, and
this has reduced some reuse options.
As well as providing a potential use for recaptured heat, metal charge
preheaters are being used to enable the reuse of oily swarf and metal chips
(FTJ, 1999g). The environmental implications, as well as the potential cost
benefits, need to be considered carefully. Another option is discussed in
Example 30.
Example 29: Reducing Baghouse Dust Waste
ANI Bradkin, a Brisbane-based foundry, currently sends its furnace
baghouse dust to secured landfill at a significantly higher cost than other
foundry by-products. The company is currently undertaking bricketting
trials that will allow the dust to be compacted into a form that can be
handled more easily and allow it to be send to unlined landfill at a reduced
cost, or potentially allow some form of beneficial reuse.
Another option being trialled is adding the material to the furnace.
Baghouse dust cannot simply be added directly to the melt because the
dust extraction system would remove it. It therefore needs to be pelletised
or bricketted to allow it to sink. While some metal recovery may be
achieved, the main purpose is to incorporate the material into the slag,
which is more stable, easier to handle and has the potential to be used as
a construction material. This could significantly reduce the cost of this by-
product to the company. The company is currently looking for suitable and
cost-effective equipment to achieve this outcome.
RMC (Reliance Manufacturing Company), a Brisbane-based foundry, is
considering options to reclaim baghouse dust which consists
predominantly of metal in oxide form. Tests indicate that dust from the
fettling area is 83% copper, 6% zinc and 4% lead, similar to the
composition of the original gunmetal. Dust from the furnace is 60% zinc
and 5% copper. The company is investigating methods to reclaim the
metal from the dust and return it to the furnace. To reclaim the metal, it
would need to be reduced from its oxide form, perhaps using a sintering
process. This would also pelletise the material allowing it to be returned to
the furnace more easily. Metal reclamation is considered to be more
viable in this operation than many others because the majority of metal
melted is gunmetal with has a high value. Foundries that melt a wide
range of metals may have more limited options in this area.
Source: Spokespersons from ANI Bradkin and RMC
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Example 30: Recovery of Foundry Dust
A UK foundry that employs 400 people and produces 25000 tons of iron
castings annually installed a wet scrubbing unit to capture fugitive dusts
from the process. The system captures over 99% of the dust, resulting in
minimal emissions. Annually the process captures 1600 tonnes of sludge,
which is internally reused in the mould-making process. The capital
investment was 拢19,000 (A$47,500) but resulted in annual savings of
拢84,000 (A$210,000) including 拢60,000 (A$150,000) for materials costs
and 拢24,000 (A$60,000) for waste disposal.
Source: ICPIC (1999)
5.4.5 Minimising Investment Shell Slurry
Another example of input reduction for the investment casting industry is
described in Example 31.
Example 31: Quality Control of Investment Shell
Inputs
Finecast, an investment casting foundry in the UK, identified the need to
improve the quality control of its casting shell slurry. Inconsistencies in the
mix resulted in unexplained events of shell cracking during de-waxing,
and breakdown and metal run-out during pouring. Initially only daily
viscosity tests of the slurry were carried out. The company implemented a
full quality-control regime, which reduced reject product attributed to shell
problems by 90%. Slurry life was also extended significantly and
productively improved.
The variables that were identified as being the key determinants of shell
quality were viscosity, temperature, pH, specific gravity, binder
percentage and bacteria counts. Appropriate tests were developed for
each of these factors.
Source: FTJ (1999k)
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6. Production Planning and Improvement
Key Points
Focusing on overall production planning and improvement can help to develop
a systematic approach to Cleaner Production in the foundry. Foundry
processes are continually being improved to achieve better economic and
environmental outcomes. Computers, automation and control systems will
continue to change the way foundries operate over the next 20 years. As well
as many challenges, these technologies will create many opportunities for the
industry.
Some of the key questions to ask in relation to production planning and
improvement include:
鈥? Do we have an effective Environmental Management System that is
integrated with our other business systems?
鈥? Can we improve the layout or streamline the process to improve the
efficiency of the operation?
鈥? Can we use production simulation technology to help redesign our
processes?
鈥? Can we utilise any computer aided technologies in the foundry (e.g. rapid
prototyping, rapid tooling, casting simulation)?
鈥? Can we benefit from undertaking a cost / benefit analyses of different
casting systems for part of all of the products or for new markets (e.g.
Investment, permanent mould, die, lost foam and vacuum casting)?
鈥? Can we develop a capability in another casting process for some of our
products (or for new markets)?
鈥? Can we improve our communication systems (e.g. electronic data
interchange, the Internet) to reduce our lead times, increase the efficiency
of the process and offer better customer services?
鈥? Can we improve scheduling and materials tracking systems?
鈥? Can we develop / improve smart controls and sensors for automatic
supervision?
鈥? Can we use / improve computer aided design tools to integrate concept
design, prototyping, pattern making and moulding?
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6.1 Process Layout and Design
Improving the layout and design of processes within the foundry can improve
the efficiency of the operation and thereby reduce the generation of waste. As
well as achieving incremental improvements by implementing some of the ideas
described in this manual, the company may benefit from taking a more holistic
view to redesigning the process. It may be possible to 鈥榙esign out鈥? wasteful
practices. If a company has been doing a process the same way for a number
of years it may benefit from investigating redesign opportunities.
As well eliminating or minimising the generation of waste materials 鈥榓t source鈥?,
improving process layout may minimise non-value-adding processes. This may
include unnecessary movement of materials into and out of the process areas,
time-consuming and wasteful processes such as over-fettling, and unnecessary
space for inventory of consumables and work in progress.
Process simulations, visits to other sites, benchmarking, identifying key
process problems and brainstorming solutions are all potential approaches to
effective process redesign. A number of management and process approaches
are discussed below and could be explored further to develop a suitable
approach to process redesign and improvement (see Example 32 and Example
33).
Example 32: Redesigning the Foundry Process
Charter Casting Limited changed its casting operation from one that had a
flow of product through different operation divisions, to a cellular working
environment. Jobs have now been reassigned to form small multi-skilled
teams working in purpose-built work areas.
The company has achieved a number of benefits from this change. Work
in progress has been reduced greatly, leading to reduced space
requirements. Direct labour costs have been reduced by around 10% due
the reduced movement of work in progress. Lead times have been
reduced and product quality has increased significantly. The reject rate
has been reduced to 3.5%. Job satisfaction and morale have improved
among team members. Teams are now responsible for production quality
and output from the work and multi-skilling has led to greater work variety.
Overall, the company has experienced a 25% growth in production due to
its increased competitiveness.
Source: The Foundryman (1997b)
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Example 33: Redesigning the Foundry Process
(A Queensland Story)
Nu-Spray is a small non-ferrous jobbing foundry in Brisbane that supplies
high-quality castings to the local market. It produces around 40 tonnes of
casting per year and uses approximately 60 tonnes of sand per month.
The company has been in operation for 5 years and has grown with
limited capital input.
The owner identified that the major problem limiting capacity was the
manual sand/binder mixing system, which was very labour intensive, took
up a lot of space and produced high levels of waste. As part of the
solution the company decided to install an automatic hopper and mixer
system. The company located suitable second-hand equipment, which
was installed during the second half of 1999. The expected benefits of the
improvement are as follows:
鈥? The time of the staff member who was responsible for mixing sand is
now available to help increase production at the foundry.
鈥? Sand and binder waste has been significantly reduced, resulting in
environmental benefits and cost savings. Previously, sand had been
stored in an area where stormwater would contaminate the stockpile
and spillage of sand and binder from the manual system was high.
鈥? Space was made available by elimination of the sand storage area.
This also helped increase production: the extra space made it possible
to redesign the process and increase the storage area for moulds.
鈥? Production capacity will increase by at least 30%. The company
expects to utilise this by capturing orders that they have previously
been unable to accept due to production constraints.
鈥? The changes, which cost less than $20,000, are expected to pay for
themselves in less than 6 months.
The company is currently investigating further opportunities for process
redesign to take advantage of the increased space. Second-hand
conveyors have been located, and these will allow the company to create
a continuous flow of production and reduce a significant amount of
manual handling.
Source: Spokesperson from Nu-Spray Foundry
Production planning simulation techniques are being developed, with a view to
streamlining production processes, making them more flexible and eliminating
production errors (FTJ, 1998c) (FTJ, 1998m). Production simulation can be
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used for a range of decisions where the mistakes in real life would be costly.
Potential uses include optimisation of existing processes, design of new
process cells, lines or whole plants, and order scheduling (see Example 34).
Example 34: Production Simulation in Foundries
The Swedish Foundry Association is pioneering the use of production
simulation techniques for use in smaller foundries. One of their clients
was reported to have problems in keeping up with the demand for molten
metal during peak pouring times. A pouring schedule was simulated,
taking into account a range of factors including the melting capacities of
the furnaces, the metal requirements for each mould, desired intervals
between pourings etc. Simulations helped the operators identify
opportunities to streamline the production process, thereby reducing the
risk of metal shortage. As a result, the foundry鈥檚 output increased by 15%.
The simulations have also helped identify and remove bottlenecks in its
coreshop.
Another company was considering the purchase of a robot that would
service two shell-moulding lines. They needed to be sure that the machine
would be able to handle the required capacity, how it would be affected by
different mould combinations, and other factors such as whether the
operator would be able to handle the workload. The initial process design
was modelled and it was shown that the robot was likely to be a
bottleneck. A number of alternatives were simulated and a new design
was developed and implemented. As a result, the company estimated that
the efficiency of the process was increased by 20% compared with the
initial design. As well as optimising the use of the robot, other bottlenecks
were identified and eliminated. Several expensive fixtures were found to
be unnecessary, and overall capital costs were thus reduced.
Source: FTJ (1998c)
6.2 Rapid Prototyping and Pattern Making
Many companies are actively developing systems that improve the efficiency of
the pattern-making process to reduce lead times and improve casting flexibility.
These approaches include the use of automated computer-aided manufacture
(CAM) tooling to produce patterns and to undertake rapid prototyping. While
they are capital intensive, rapid tooling machines can achieve high levels of
accuracy in pattern design.
The Castings Development Centre in the UK, for example, is developing
technology that can machine moulds directly from compacted resin-coated
sand, eliminating the need to produce and maintain patterns (FTJ, 1999j). This
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system is reported to achieve high rates of production and equivalent
dimensional accuracy, and can be cost effective for developing prototypes or
for single units or small production runs.
Prototypes are needed when testing must be carried out prior to full-scale
production, using parts with properties that are the same as, or functionally
similar to, those of the production parts. As computer-aided design (CAD)
technology has become more common, this has led to the development of a
range of techniques commonly called rapid prototyping. These systems
effectively allow the designer to 鈥榩rint鈥? a three-dimensional solid model of their
design from a CAD design. This prototype can then be used as a proof of
concept and allow detailed form, fit and function testing to be undertaken
without the necessity to develop expensive tooling. Among their many benefits,
these techniques:
鈥? reduce time and resources required to develop a new product;
鈥? allow design problems to be identified early;
鈥? can provide the master pattern for hard tooling systems or temporary
patterns for single unit or limited production runs;
鈥? significantly reduce lead times for product development. The system has
been demonstrated to reduce prototype development to as little as 2鈥?4 days
and final part manufacture to 1鈥?4 weeks (depending on part geometry). This
is compared to 18鈥?20 weeks for conventional methods (Solid Concepts,
1997).
The three most common systems that have been developed are:
鈥? Stereolithography (SLA) process, developed by 3-D Systems, Inc.;
鈥? Selective Laser Sintering (SLS) process developed by the DTM
Corporation; and
鈥? Laminated Object Manufacturing (LOM), developed by Helisys Inc.
The SLA and SLS processes both build up complex three-dimensional models
by successively layering material using laser deposition. The SLA process (see
Figure 11)uses a photopolymer liquid resin that is cured using a UV laser. The
SLS process uses powdered metal which is fused (sintered) by heat generated
from CO2 laser (Durham and Grimm, 1996).
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Figure 11: Schematic Drawing of Stereolithography
Apparatus (SLA)
Source: Dolenc (1994)
The LOM process (see Figure 12) divides the 3-D model into thin 2-D layers. A
laser is used to cut the shapes into thin sheets (i.e. paper, plastic, ceramic)
which are laminated together to build up the model (BIBA, 1998).
Prototyping technology can also be used to produce final castings. The SLA
process has been adapted so that prototypes can be used as patterns for
investment casting processes. This can greatly reduce the cost of developing
new investment products. For a single unit or for limited production runs, rapid
tooling of patterns can bypass the expensive and time-consuming step of
machining hard tooling.
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Figure 12: Schematic Drawing of Laminated Object
Manufacturing System (LOM)
Source: Dolenc (1994)
Rapid prototyping technology is currently being developed in Australia by a
number of groups, including the Queensland Manufacturing Institute Ltd (QMI,
1998) and the CRC for Alloy and Solidification Technology (CAST, 1999).
Factors that should be considered when investigating the use of rapid
prototyping include:
鈥? The availability of 3-D CAD modelling capabilities. Companies are
increasingly using these techniques for design or tooling, so it is becoming
less of an issue.
鈥? Scale of the operation. The relatively high cost of rapid prototyping tends
to restrict smaller foundries from developing an in-house capability.
Outsourcing may be an option, however, and there are a number of centres
in Australia that offer rapid prototyping services.
鈥? Part complexity. In general, the cost effectiveness of rapid prototyping
improves as part complexity increases.
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鈥? Part size. Current systems are restricted to smaller parts.
鈥? The importance of short lead times. Where timing is an important
competitive consideration, rapid prototyping can be of significant economic
benefit (Metal Asia, 1999a).
For more information about rapid prototyping and related technologies, visit the
BIBA Internet List of Worldwide Rapid Prototyping Sites at:
http://www.biba.uni-bremen.de/groups/rp/rp_sites.html
6.3 Changing Casting Processes
Casting processes are continually being improved. This includes the
optimisation of particular casting techniques for specific applications and the
extension of casting techniques to other castings (i.e. larger or smaller scales,
different metals, geometric complexity etc.). Companies can benefit from
continually monitoring developments in innovative casting technologies and
process improvements that could be applicable to their products.
Precision casting techniques, such as investment casting, lost foam and die
casting, have high dimensional accuracy and can produce 鈥榓s net鈥? castings that
require almost no fettling or polishing. They can also significantly reduce the
generation of by-products such as sand, and eliminate or reduce the use of
inputs including binders and other consumables.
While it is clearly a strategic decision, companies could benefit from
undertaking an analysis of how different casting systems could benefit their
operations. This section briefly highlights a few innovative processes that have
been adopted by foundries to achieve cost savings and environmental
improvements. More detailed descriptions, including the major advantages and
disadvantages, are provided in Part 5.
Vacuum moulding. This extension of conventional sand moulding eliminates
binder use and virtually eliminates sand waste. The process also achieves
significantly higher dimensional accuracy and metal yield than conventional
processes. This process is applicable to all sizes of castings and most metals,
and can be very economical and energy efficient (UNEP, 1997).
Lost foam casting. The major benefits of this process include the virtual
elimination of waste sand, the looser packing of sand, the elimination of cores
from the design process and the simplification of the production process.
Because multiple parts are typically mounted on a single tree, significant
economies can be achieved throughout the production process, particularly for
complex castings (Environment Canada, 1997). One company has reportedly
reduced fettling costs by 66% using this process (FTJ, 1998g).
Investment casting. This process typically achieves the highest dimensional
accuracy and requires the least amount of fettling and cleaning. Metal and
sand yields and melt efficiencies are relatively high. The Replicast process has
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successfully adapted these techniques to make it suitable for some larger
castings.
Semi-solid metal casting. This process, which is an extension of die casting,
combines many of the advantages of casting and forging. The major
advantages include lower energy intensity, increased metal yield and structural
integrity.
These and other techniques (described further in Part 5) should be reviewed by
companies to assess their relative benefits for the products produced and
markets served by the company. There is also the potential to undertake in-
house research and development to develop a modified process which is
optimised for the specific production requirements of the company.
A feasibility analysis of different casting techniques should consider all the
major costs and benefits. As an example, Table 11 lists many of the different
aspects that could be considered when comparing the costs and benefits of lost
foam casting and convention sand casting.
Table 11: Comparing Costs and Benefits of Lost
Foam and Conventional Sand
Materials Energy Occupational Health
鈥? Sand 鈥? Pattern making and Safety
鈥? Lost time to injuries
鈥? Binders 鈥? Tooling
鈥? Training
鈥? Polystyrene 鈥? balls 鈥? Moulding preparation
requirements
鈥? Polystyrene 鈥? blocks 鈥? Transport of moulds
鈥? Capital
鈥? Paint 鈥? Pouring
requirements
鈥? Ceramic tubes 鈥? Knockout
Rework and defects
鈥? Exothermic sleeves 鈥? Fettling
Space
鈥? Plastic sheet By-products
Environmental
鈥? Sand
鈥? Water compliance
鈥? Slag
鈥? Tooling 鈥? Training
鈥? Baghouse dust
Labour requirements
鈥? Pattern making 鈥? Shotblast 鈥? Capital
鈥? Tooling 鈥? Metal fines requirements
鈥? Moulding preparation 鈥? Foam cuttings 鈥? Maintenance
鈥? Transport of moulds 鈥? Timber
鈥? Pouring 鈥? General foundry wastes
鈥? Knockout
鈥? Fettling
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6.4 Communication Tools and Integrated Control
Systems
Computer technology will have an increasing impact on the foundry industry in
the future (see Example 35). A whole range of communication tools are
continually being developed and, while they can create significant challenges,
they also present incredible opportunities for developing innovative and
efficient systems to deliver excellent customer service.
As well as computer-aided design and manufacture (CAD/CAM) and automated
process control, communication systems are undergoing a massive
transformation. All companies should maintain a close watch on these
technologies and develop appropriate strategies to ensure their commercial
competitiveness (Metal, 1997c). These technologies include electronic data
interchange (EDI) and the Internet, as well as a range of improving systems in
office and foundry management.
Example 35: A Vision for 2010 鈥? Communication and
Control Systems in a State-of-the-art
Foundry
The following description of a customer order to MetalCast Ltd (a
hypothetical company in the year 2010) provides a vision of how modern
communication and control systems are likely to impact on the foundry
industry in the near future. All the technologies discussed are currently
available and will develop significantly and become more integrated over
the next decade.
a) After conducting an Internet search, a customer finds the home page
of MetalCast. Impressed by the valuable information and interactive
design tools that are available online, the customer is able to develop
an effective design and accurate specifications.
b) The customer sends specifications and detailed 3-D design data via e-
mail (CAD files) to MetalCast. Using casting simulation software (see
section 3.1.6), MetalCast estimates the cost and provides a quote by
e-mail.
c) On confirmation of the order, the customer is given a unique order
code that will allow them to track the progress of the order directly via
the Internet. MetalCast designs an efficient gating system and
recommends some design changes that reduce the net weight of the
cast and improve the cast strength and quality.
d) On confirmation of the order, the automatic purchasing system sends
electronic orders to the each of their suppliers to ensure just-in-time
delivery of the necessary consumables.
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e) After design approval, the CAD data is sent to the rapid prototype unit
and a 3-D prototype is produced (see section 6.2). This is sent to the
customer for proof-of-concept testing. After prototype approval, the
order is placed in the production scheduling system.
f) The prototype is used to create a permanent pattern which is bar-
coded for automated storage and retrieval for future orders. Bar codes
are also used for each flash and later for individual units to track the
product from the mould room and through pouring, finishing and
dispatch.
g) When the order is ready to be processed, the work computer provides
the job details (i.e. number of units, flasks and other special
instruction). Work instructions and easy-to-follow demonstration videos
are readily available on the system if staff need any additional
information.
h) The pattern, flask and other consumables are delivered automatically
by a series of overhead robotic cranes to the mould and core room.
This eliminates the need for operators to spend time moving materials
to and from the workspace, thus saving time and reducing the risk of
accidents. Inventory records are altered accordingly.
i) The prepared flasks move to the pouring area where the metal has
been prepared on a just-in-time basis to minimise holding times. Bar
code scanners on the conveyors track progress and report on any
bottlenecks. This helps identify opportunities for process
improvements. Scales and sensors on the conveyors record the weight
of the flasks at each stage to accurately calculate a range of efficiency
measure including metal and sand yield. This helps identify key areas
of waste and inefficiency.
j) After moving through the robotic fettling and cleaning area, the
products are sent to dispatch for packaging. The customer is
automatically e-mailed, to inform them that the order has reached the
dispatch area and is scheduled to arrive at their premises the following
morning. Invoices are automatically prepared and sent.
Electronic data interchange (EDI) is the basis of systems that share electronic
information between customers and suppliers, and can greatly reduce the use
of paper, reduce error and increase the speed of transactions. Information that
can be exchanged electronically includes customer orders and specifications,
supplies requisitions and design data such as CAD files (see Example 36).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 36: Signicast Corporation 鈥? Continuous
Flow Manufacturing
Signicast Corporation, an advanced investment casting corporation in
Wisconsin, USA, has redesigned its process from a jobbing shop to a
continuous flow manufacturing (CFM) system. As a result, delivery times
have been cut by 90% (1鈥?2 weeks versus 8鈥?12) while costs have been
reduced and quality and flexibility improved. The two major objections that
potential clients have about investment castings are lead times and price.
As a result of these changes, sales have more than doubled sales, to over
US$65 million (A$100 million).
CFM is an integration of production, material handling and information
processing. The system, which was designed around a greenfield site,
incorporated a number of elements:
鈥? development of a just-in-time parts delivery system;
鈥? development of stand-alone production modules that were each
designed around standardised product range;
鈥? standardisation of machinery and automation of processes where
possible, which includes:
鈾? three automatic storage/retrieval systems. One handles the pick-
up and delivery of dies, sprues and moulds on cluster pallets in
the wax cell. The other two move totes containing moulds in
production;
鈾? four robots to keep moulds in sequence and flowing continuously
through the plant.
Signicast has achieved a product throughput of 4.3 days without heat treat
and 6.3 days with heat treatment. Labour costs were reduced by 25%.
The quality control and analysis process has shifted from lot traceability to
mould traceability. Having a batch size of one means that problems are
quickly identified and solved, eliminating rework loops. Automation has
also removed much of the drudgery of the work and allowed operators
more time to focus on producing quality products.
Source: Signicast (1999)
The Internet has developed rapidly over the last decade but will develop even
more over the next. The potential to use this technology in the foundry industry
is immense and is likely to revolutionise how all businesses interact with their
customers, suppliers and other stakeholders (see Example 37). Some ideas
that could be applied by the foundry industry and individual companies include
the following:
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? Online casting information. The industry or individual companies could
develop information about the casting processes to help customers develop
better designs and specifications. Tools could be developed to help
customers work out which casting process would be most cost effective and
to demonstrate the benefits of casting techniques over forging and
machining.
鈥? Integrated ordering, production, product tracking and delivery
systems. Customers could use the Internet to submit electronic orders. This
could include design information in the form of CAD files. When production
scheduling is integrated into this system, there is the potential to offer
product tracking information to customers (see Example 37). Foundry
customers could potentially use this service or be sent notification by e-mail
informing them of progress. This information would help them plan their own
processes more effectively.
鈥? Purchasing and inventory management. The Internet can also be used to
integrate with suppliers and to develop more effective just-in-time inventory
systems.
鈥? Intranets. The technology can also be used to develop Intranets 鈥?
information systems that are available only in-house or to an approved
group of individuals. This can be used to protect commercially sensitive
information or to develop in-house information systems. This could include
online manuals for quality assurance and other management systems.
鈥? Training. Training for quality management, environmental management,
health and safety and other issues typically involves the development of
complicated written procedures and work instructions. Internet/Intranet-
based training could incorporate video files that present easy-to-follow
demonstrations of how to undertake an activity. Companies are also
beginning to use the Internet to disseminate corporate information to staff.
鈥? Process control. It is likely that the Internet will increasingly incorporate
and even replace the current process control systems. This has the
potential to greatly reduce the cost of control and make it more accessible
to non-technical staff. A range of shop-floor monitoring technology is being
developed, including the use of bar codes on work orders to track progress.
鈥? Environmental management. Increased process control and monitoring
has the potential to greatly enhance the ability of companies to
management their environmental aspects more effectively and efficiently.
Cleaner Production benefits should flow from this increased control.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Example 37: Reducing Pattern Lead Time Through
Integrated Communication
Independent Steel Castings Company (ISCCO), a precision investment
casting company located in Michigan, USA, uses the Internet to increase
the efficiency of the tooling and prototype stage. Customers can now send
engineering data in the form of CAD files over the Internet. These are then
sent to the toolmaker, who uses computer software that is capable of
using the CAD data to develop tool-cutting information. This computer
transcribes the data and sends it directly to a 鈥榮ix axis cutting machine鈥?. A
prototype of the new pattern mould is then quickly roughed out using an
aluminium plate. Only shrink allowances and polishing have to be added
to the mould. This system has reduced tooling lead time to less than 3
weeks.
Other features of the company鈥檚 communication system include: a
quotation tracking system that enables them to respond to requests within
48 hours; order tracking facilities that schedule production, monitor
backlogs, and guarantee delivery date; computer-aided design,
production and quality management; preventive maintenance; general
inventory and financial and office management functions. This integrated
system has allowed the company to achieve turnaround times of as little
as 5 weeks.
Another service that the company can provide, using its 3-D CAD
technology, is an engineering comparison of its investment casting
process with other options such as machining and welding. This helps the
company demonstrate the potential cost savings and other production
advantages that their customers can achieve from changing to the casting
process.
Source: ISSCO (1999)
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7. Conclusions
Cleaner Production can bring about financial savings, improve environmental
performance, enhance compliance, and improve product quality. The case
studies described in this section suggest that most foundries could significantly
to improve their bottom line and reduce the impact of the operation on the
environment. Even companies that have expended a major effort on process
improvement should continually review emerging Cleaner Production.
As shown in this report, there are the gains to be made throughout the foundry
and these improvements do not necessarily have to come at a great price.
While there are a number of barriers to implementing Cleaner Production, the
benefits are real.
More than simply listing opportunities for improvements, as in this report,
companies should consider Cleaner Production strategically as a way of doing
business. Companies that successfully implement any management or
improvement system, such as quality management systems, environmental
management systems, safety or hazard management systems achieve that
success because senior management uses the system to better manage the
business.
For the most successful companies, Cleaner Production is not something
extra that they do when they take time out from managing the business.
It becomes an integral part of how the business is run.
Part 6: Cleaner Production Implementation Guideline provides an overview for
develop a strategic approach to Cleaner Production. By using Cleaner
Production as a tool for managing their business, senior managers and foundry
owners can use the approach to drive changes throughout their operation. By
taking a strategic approach to minimising waste and maximising resource
efficiency and productivity, Queensland foundries will be better able to compete
in the increasingly competitive castings market.
Page 91
Part 3:
Case Studies
Case Study 1: Dana Corporation
Industry Heat-Treating
Source: http://www.aceee.org/p2/p2cases.htm
Case Study 2: Decatur Foundry, Inc.
Infrared Drying
Source: http://www.aceee.org/p2/p2cases.htm
Case Study 3: Republic Engineered Steels, Inc.
Scrap Metal Recycling and Water Reuse
Source: http://aceee.org/p2/p2cases.htm
Case Study 4: Chaparrel Steel Company
Waste Re-use
Source: http://www.aceee.org.p2/p2cases.htm
Case Study 5: Progress Casting Group, Inc.
Aluminum Foundry Replaces TCA with Water-based Coatings
Source: http://www1.umn.edu/mntap/P2/FOUND/cs93-e1.htm
Case Study 6: Wolverine Bronze Company
Low Energy Recycling of Foundry Sand
Source: http://es.epa.gov.techinfo/michigan/mich-cs4.htm
Case Study 7: Francis W. Birkett & Sons Limited
Foundry Casts Net Over Sand Waste
Source: http://www.waste-management.co.uk/studies.birkett.htm
Case Study 8: Ashley Forge
Common Sense Approach to Hard Waste Savings
Source: http://www.waste-management.co.uk/studies.ashley.htm
Case Study 9: KHD Humboldt Wedag
Reducing Foundry Sand and Reducing Stack Emissions
Source: http://www.unepie.org/icpic/castu/castu152.html
Case Study 10:Triplex Alloys Ltd.
Thermal Reclamation of Chemically Bonded Foundry Sand
Source: Kay.Montandon@aeat.co.uk
Case Study 11:Empire Castings
Culture Change
Source: http://www.deq.state.ok.us/empire2.htm
The remainder of the manual is available on the net at:
http://www.geosp.uq.edu.au/emc/CP/foundry.htm
Cleaner Production
Self Assessment Guide
Metal Casting Industries
The UNEP Centre for Cleaner Production
and
The CRC for Waste Minimisation and Pollution Control, Ltd
October 1999
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
Contents
1. WHAT IS CLEANER PRODUCTION? .....................................3
2. HOW TO USE THIS GUIDE .......................................................3
3. THE BENEFITS OF CLEANER PRODUCTION .....................3
3.1 SAVING MONEY ......................................................................................... 3
3.2 PREVENTING POLLUTION............................................................................ 4
3.3 COMPLYING WITH ENVIRONMENTAL LEGISLATION..................................... 4
4. THE IMPACTS OF METAL CASTING WASTES ...................4
5. HOW DO I ACHIEVE CLEANER PRODUCTION?................5
5.1 ELIMINATE................................................................................................. 6
5.2 REDUCE..................................................................................................... 6
5.3 REUSE ....................................................................................................... 6
5.4 RECYCLE ................................................................................................... 6
5.5 TREAT AND DISPOSE .................................................................................. 6
6. CLEANER PRODUCTION ASSESSMENT CHECKLISTS ....7
7. SOURCES OF INFORMATION .................................................7
8. CONTACTS...................................................................................7
Self Assessment Guide 2
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
1. What is Cleaner Production?
Cleaner production aims to prevent pollution, reduce the use of energy, water and material
resources and minimise waste profitably, all without reducing production capacity.
It involves rethinking conventional methods to achieve 鈥榮marter鈥? products, product
components, and production processes.
While casting operations are relatively clean, all casting operations have some potentially
harmful to the environment, the health of their employees and to generate nuisance issues in
the community. The direct costs of treating and disposing of these wastes can be high and the
trend is towards increasing costs for business and for the community. The true cost may be
much higher still when the social costs of extracting virgin materials and creating large landfills
is taken into account.
Treatment and disposal of waste generally only address the symptoms of an inefficient process.
Waste may be an indicator that you are losing money unnecessarily.
Cleaner Production aims to reduce waste and inefficiency at source.
It can save you money!
2. How to Use this Guide
This Self Assessment Guide is designed to help you explore the opportunities for Cleaner
Production in your organisation. This Guide suggests the following five simple steps to
implement Cleaner Production in your operation:
鈥? Measure use of chemicals and consumables and measure the waste generated;
鈥? Identify causes of waste generation;
鈥? Identify opportunities to reduce waste;
鈥? Evaluate the viable options; and
鈥? Implement the best options and review the improvements.
The tables and checklists which make up this guide have been provided in a tear out section to
assist you in carrying out these steps. Once changes have been implemented you can use the
tables again to check your progress.
Many of the commonly recognised areas for reducing waste in the Metal Casting industry are
listed in the Guide to get you started. Extra space is provided for you to include information
that is specific to your operation and any Cleaner Production ideas of your own.
3. The Benefits of Cleaner Production
The major benefits from a Cleaner Production program are:
3.1 Saving Money
Cleaner Production can save you money through better use of your valuable resources. For
example, savings can be achieved in the areas of:
鈥? wasted raw materials;
Self Assessment Guide 3
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
鈥? water and energy consumption;
鈥? waste treatment and disposal.
Cleaner Production strategies typically cost less than treatment and disposal (so called 鈥榚nd-of-
pipe鈥?) technologies. Complying with the discharge limits set by Council the through on-site
treatment can be a significant cost, may require specialist knowledge and generally provides no
profit for the organisation.
Cleaner Production, on the other hand, focuses on improving your core business. Companies
can often perform better than their environmental requirements as an outcome of running a
profitable and efficient business. Many strategies, such as housekeeping and process
improvements, can be implemented at a low cost and can have immediate benefits. Changes to
plant and equipment will require capital but many Cleaner Production projects that have been
undertaken show that they can pay for themselves in less than one year.
3.2 Preventing Pollution
Cleaner Production is about preventing pollution, reducing the use of energy, water and
material resources and minimising waste, without reducing production capacity.
Businesses are encouraged to review work practices and processes throughout the entire
operation to identify ways to reduce waste at the source rather than trying to control pollution
at the 鈥榚nd-of-the-pipe鈥?.
3.3 Complying With Environmental Legislation
Cleaner Production will assist in maintaining or improving compliance with relevant
environmental legislation. This can bring a number of benefits such as reduced regulatory
intervention, possible reduced licence fees and charges and better control over your business.
Regulations regarding the transport and disposal of wastes are becoming tougher. In
Queensland, regulations are being formulated to include waste minimisation and Cleaner
Production under the Environment Protection Act 1994 (EPA) so these issues are rapidly
becoming a reality for industry.
4. The Impacts of Metal Casting Wastes
Foundries are often perceived as being dirty and environmentally unfriendly. However, most
modern foundries are relatively environmentally benign in comparison to other industrial
activities in the metal sector (e.g. smelting and metal finishing), and most of the by-products
generated by the industry have relatively low impacts. The major issues facing the industry are
the large volumes of by-products that are currently being sent to landfill, nuisance odours, and
the need to maximise health and safety in the industry.
Sand is the largest by-product generated by volume in this process. Even in operations that
undertake a high level of reclamation, some new sand is required to maintain the quality of the
sand in the system. As a result some sand is lost from the system. This may be sent to landfill,
reclaimed off-site or put to beneficial reuse. Foundry sands from ferrous foundries are not
usually considered to be hazardous, typically passing TCLP (toxic characteristic leaching
procedure) tests, and can be sent to unlined landfill. Some non-ferrous sands contain high
quantities of heavy metal, which requires them to be sent to secured landfill sites. Most of the
chemical binder used in core and mould making is burnt off during the pouring process.
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Binders in waste sand can become an important issue if large volumes of resin-coated sands are
wasted before the pouring stage. Binders and salts can build up to unacceptable levels over
many reclamation cycles, so careful monitoring and testing is important.
Baghouse dust from the mould and core shops and from the shotblasting operations is typically
the second largest by-product generated by volume in sand casting processes. Sand grains are
broken down into fines and dust, particularly after multiple reuse, and this can affect casting
quality and also create occupational health and safety issues (e.g. silicosis).
Slag is another significant by-product stream by volume. Flux is a material added to the furnace
charge or to the molten metal to remove impurities. Flux unites with impurities to form dross
or slag. This rises to the surface of the molten metal, from where it is removed before pouring.
When cooled this forms a relatively inert complex glass-like structure which can usually be
disposed of in unlined landfill or put to beneficial reuse.
Other solid wastes generated in sand casting operations include:
鈥? refractories (furnace and ladle lining);
鈥? drums;
鈥? spent shot;
鈥? metal swarf and shavings;
鈥? timber pallets and timber from the pattern room;
鈥? general foundry waste including packaging and consumables (e.g. rags, gloves, grinding
wheels etc).;
鈥? general office and lunchroom wastes.
Foundries also produce small quantities of liquid by-product streams. The major sources are
cutting fluids, hydraulic and other oils, solvents, waste paints and paint sludges, uncured and
cured binders and waste catalysts (acids and bases). Water streams are also generated from
quenching baths, cooling systems and other minor sources.
Air emissions from the process typically include carbon monoxide, organic compounds,
hydrogen sulfide, sulfur dioxide, nitrous oxide, benzene, phenols, and other hazardous air
pollutants (HAPs). The actual emissions depend on a number of factors including the type of
metal poured, the cleanliness of the charge, the types of binders used and the melting and
pouring practices employed. A portion of the metal (around 3%) volatilises during the melting
and pouring process. The major environmental issues related to these fugitive emissions are
usually those of occupational health within the foundry and nuisance odours outside the
foundry (USEPA, 1998).
5. How do I Achieve Cleaner Production?
In adopting a Cleaner Production philosophy, try to consider how wastes were created rather
than how they can be treated. Record keeping of raw material inputs and outputs, assisted by a
monitoring program (perhaps regular audit checks) may help better manage raw materials, and
help identify areas where improvements can be made.
Minor improvements in housekeeping and procedures may be all that is required to reduce
unnecessary losses of raw materials from leaks and spills. In other cases more significant
changes to the process, equipment or layout may be required to achieve improvements.
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Considering the Cleaner Production hierarchy helps to focus on options to eliminate or reduce
waste at source.
5.1 Eliminate
Elimination the need to
use hazardous materials Cleaner Production - An Integrated Approach
can greatly operating
costs and reduce the
potential environmental
Focus Strategy
harm. For example, by
substituting hazardous Eliminate Pollution
Prevention
materials with less
Reduce
harmful alternatives and
Waste
standardising the range Reuse
Management
of chemicals or alloys
Recycle
used.
Treat & Control &
5.2 Reduce
Dispose Disposal
Where use of certain
materials can not be All media Impact of
eliminated, try to Air, Water, Soil Products
minimise their use. Personnel Management
Raw Materials Use Energy
There are many Work Procedures
opportunities to reduce
waste and resource use in the foundry. Examples include improving the energy efficiency of
furnaces and ancillary services, improving the metal yield in the operation by improving casting
design and, improving pouring practices; and reducing sand waste through effective
reclamation systems.
5.3 Reuse
There are many opportunities to reuse 鈥榳aste products鈥? in the metal finishing industry. This
will reduce the demand for raw materials and the cost of treatment and disposal. By-product
reclamation such as sand, shot and swarf are examples of the opportunities in this area. Some
foundries may be able to reclaim heat from the process.
5.4 Recycle
Are the wastes identified by your assessment really 鈥榳astes鈥?? Can some of these be reclaimed
through simple treatment processes that enable them to be reused on-site. Other by-products
that cannot be used on site may be able to go off site for recycling or beneficial reuse. In these
cases there may be the potential to sell recyclable items and also save indirectly by the avoiding
disposal costs.
5.5 Treat and Dispose
This option should only be considered after the other options have been exhausted. Generally
these options are typically a cost to industry. However it may be essential to consider this as a
part of your overall Cleaner Production strategy.
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6. Cleaner Production Assessment Checklists
The first step in developing a Cleaner Production program is to get a good picture of the
resources used and the wastes that are generated in your organisation. This will help you to
identify the areas that are costing you money and harming the environment and will help you
assess the costs and benefits of implementing Cleaner Production options.
This Guide has been designed to help companies meet their requirements under the new
Environment Protection Program (EPP) for Waste to develop and implement a Cleaner
Production Plan. By undertaking the steps recommended by this Guide companies can help
improve their bottom line and their environmental performance.
7. Sources of Information
You will already have access to most of the information you need to carry out your Cleaner
Production analysis. This information will help you to calculate the quantity and full cost of
your raw materials and wastes including materials, labour, maintenance, cleaning and utilities.
Some of the major sources of information will include:
鈥? process descriptions and specifications; 鈥? trade waste agreement and council rates
notices;
鈥? equipment specifications;
鈥? cleaning contract records;
鈥? quality assurance procedures and
鈥? flow meters;
records;
鈥? purchasing, invoice and inventory 鈥? Materials Safety Data Sheets (MSDS);
records; 鈥? information from suppliers; and
鈥? production and scheduling records; 鈥? specific monitoring programs.
In many companies, these systems are designed to account for production and sales - not
wastes. Therefore, it may take some work to get a good picture of waste. Are there
opportunities to improve these systems to better account for resource use and wastage?
8. Contacts
If you would like any further assistance or information please contact one of the following
people:
Name Organisation Telephone
Philip Glew Chair, Cleaner Production Project Steering Group, RMC 3252 3646
(Reliance Manufacturing Company) Pty Ltd.
Bob Pagan UNEP Working Group for Cleaner Production, 3365 1594
Queensland University.
Ken McKeon Queensland EPA - Sustainable Industries Group. 3227 8925
Helen Jentz The CRC for Waste Minimisation and Pollution Control, 3244 1777
Ltd.
Dr Bill Clark The CRC for Waste Minimisation and Pollution Control, 3365 6464
Ltd.
Self Assessment Guide 7
CLEANER PRODUCTION
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Water Checklist
Water Use Monthly Use
Quantity Value
Water Used (water in)
Trade Waste (water out)
Volume
BOD5 or TOC
Suspended Solids
Oils and grease
Total Cost
Water Application
Appliance Flow rate Time in Daily Cost Percent What can we do
(litres/min) Use consumption per of Total to reduce?
(hours) (litres/day) month
Domestic use
Quench tanks
Cooling
towers
Self Assessment Checklists 8
CLEANER PRODUCTION
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Energy Checklist
Fuels Used Monthly Use
Quantity Value
Electricity
Gas
Coal / coke
Oil
Energy Application
Appliance Time in use Daily Cost per Percentage Action (eliminate,
(Hours) consumption month of Total reduce, recycle)
(kWh)
Heaters
Rectifiers
Other (Pumps)
Furnaces
Heat treatment
Self Assessment Checklists 9
Product Checklist
Resource Type Raw Materials Wastes Total Cost Rank
(add values and costs)
Product* Quantity Value Quantity Lost Treatment Disposal Cost Toxicity
(kg/month) (kg/month) Product / Handling Cost
Value Cost
Metals
Alloys
Sand
Refractory Material
Furnace lining
Ladle lining
Paint
Consumables
Sleeves
Filters
Solvents
Oils and emulsions
Aerosols
Cleaning solutions
Other Products
Oil filters
Batteries
Rags
Packaging
Paper
Resource Type Raw Materials Wastes Total Cost Rank
(add values and costs)
Product* Quantity Value Quantity Lost Treatment Disposal Cost Toxicity
(kg/month) (kg/month) Product / Handling Cost
Value Cost
Cardboard
Glass
Plastic
Rags
Empty drums
Other
* Note that these are suggestions only - include items that are appropriate to your operation.
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
Cleaner Production Options
Use this Checklist to help identify options that may be suitable to help address the key problem
areas identified in the previous tables. The ideas presented range from simple and inexpensive
to complex options. Each is explained further in the manual accompanying this Guide. If a
specific option is not relevant to your organisation, you may be able to adapt an idea or
principle. Think laterally about your operation, ask 鈥榳hy鈥? and 鈥榳hat if鈥? type questions, and
you may come up with many more opportunities to profit from Cleaner Production.
CP Option Questions Relevance (Tick One)
Not Current Potential
Relevant Practice Option
鈥? Is the state of general housekeeping affecting the
Housekeeping
flow of work or causing spills?
鈥? Are materials and chemical supplies being stored
appropriately to minimise the risk of damage or
waste?
鈥? Can just-in-time purchasing practices be
implemented to reduce the cost of inventory
management and avoid waste from out-of-date
materials (e.g. resins, catalysts and paints)?
鈥? Can preventive maintenance be use to optimise the
efficiency of major equipment and ancillary
systems (e.g. furnaces, natural gas leaks etc.)?
鈥? Can we improve staff training programs to increase
awareness about Cleaner Production or to provide
skill that increase operator efficiency?
鈥? Can we provide incentives (financial and non-
financial) to increase participation in Cleaner
Production?
鈥? Can we work with scrap suppliers to improve the
Alternative
quality of the charge material to avoid
inputs
contamination?
鈥? Can we alter the metals and alloys that we use to
improve casting quality?
鈥? Can we improve our materials testing procedures
to improve product quality and reduce waste?
鈥? Can we improve sand quality to improve the
dimensional accuracy of the cast?
鈥? Can we change the type of binders and other
additives to improve cast quality, increase reuse
options, improve environmental performance etc?
鈥? Can we change the type of refractory material used
in the process?
鈥? Can we change from solvent based coating systems
to water-based systems?
鈥? Can we alter the pattern or die materials to
improve process performance?
Self Assessment Checklists 12
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
CP Option Questions Relevance (Tick One)
Not Current Potential
Relevant Practice Option
鈥? Are there any new consumables (e.g. risers, sleeves
etc.) that will improve casting efficiency?
鈥? Can we change the type of energy used in the
process to improve efficiency and environmental
performance (e.g. natural gas etc.)?
鈥? How many tonnes of metal do we melt for each
Metal yield
tonne of usable castings? What are the major areas
of loss (e.g. melt losses, spilt metal, pigged metal,
runners and risers, reject castings, or grinding
losses)?
鈥? Can any of these areas of metal loss be reduced by:
鈥? minimising metal spills, over- or under pours
thorough precision pouring techniques?
鈥? redesigning the gating system to make it more
efficient?
鈥? using casting simulation technology to improve
cast design and solidification properties?
鈥? working with our customers to redesign the
casting to reduce it鈥檚 weight or improve its
casting characteristics?
鈥? minimising grinding losses or even eliminate
some fettling operations from the foundry?
鈥? using metal filtering, direct pouring techniques
or other methods to minimise inclusions in the
metal?
鈥? Can we redesign, optimise or change the casting
process used to increase the metal yield?
鈥? Have we undertaken a recent detailed assessment
Energy
of energy efficiency in the foundry?
efficiency
鈥? Can we benefit from implementing an energy
monitoring program to manage energy use for
either the whole foundry or for major equipment
such as furnaces?
鈥? Can we optimise the efficiency of our metal
melting and holding processes (e.g. 路 change
technology, better insulation, use protective covers
over the melt; put a cover on the pouring ladle)?
鈥? Can we optimise the efficiency of the ancillary
services in the operation?
鈥? Can we benefit from investing in automatic energy
control systems to shut down equipment when not
in use?
鈥? Can we develop greater staff awareness of energy
efficiency and run an effective 鈥榮witch-off鈥?
program?
Self Assessment Checklists 13
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
CP Option Questions Relevance (Tick One)
Not Current Potential
Relevant Practice Option
鈥? Can we improve the ladles and refractory materials
used in the furnaces and to improve energy
efficiency?
鈥? Can we recover energy from any sources for reuse
elsewhere in the foundry?
鈥? Can we benefit from investing in energy efficient
equipment and up-grading old equipment (e.g.
lighting, ladle preheating, sand reclamation,
furnaces etc.)?
Minimising by- 鈥? Have we calculated the full cost of by-products to
the company (including purchasing, processing,
products
disposing and compliance costs)?
鈥? Do we effectively segregate our by-product streams
to improve internal and external reuse options and
reduce the cost of disposal?
鈥? Do we have an effective strategy in place to
minimise each major waste stream?
鈥? Can we improve the casting design process to
minimise sand use (e.g. better flask utilisation)?
鈥? Are there other areas of the operation we can
improve to minimise sand waste (e.g. minimise
spills)?
鈥? Can we implement computer aided sand mixing
systems to minimise sand and binder use?
鈥? Do we regularly investigate and trial new binder
systems?
鈥? Can we improve the efficiency of our sand
reclamation system?
鈥? Can we minimise other foundry by-products or
reduce the demand for consumables?
鈥? Once by-products have been minimised as much as
possible, are there any beneficial reuse options that
minimise the cost of managing the material?
鈥? Do we have an effective Environmental
Production
Management System that is integrated with our
planning and
other business systems?
improvement
鈥? Can we improve the layout or streamline the
process to improve the efficiency of the operation?
鈥? Can we use production simulation technology to
help redesign our processes?
鈥? Can we utilise any computer aided technologies in
the foundry (e.g. rapid prototyping, rapid tooling,
casting simulation)?
鈥? Can we benefit from undertaking a cost / benefit
Self Assessment Checklists 14
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
CP Option Questions Relevance (Tick One)
Not Current Potential
Relevant Practice Option
analyses of different casting systems for part of all
of the products or for new markets (e.g.
Investment, permanent mould, die, lost foam and
vacuum casting)?
鈥? Can we develop a capability in another casting
process for some of our products (or for new
markets)?
鈥? Can we improve our communication systems (e.g.
electronic data interchange, the Internet) to reduce
our lead times, increase the efficiency of the
process and offer better customer services?
鈥? Can we improve scheduling and materials tracking
systems?
鈥? Can we develop / improve smart controls
and sensors for automatic supervision?
鈥? Can we use / improve computer aided
design tools to integrate concept design,
prototyping, pattern making and moulding?
Self Assessment Checklists 15
CLEANER PRODUCTION
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Evaluation of Cleaner Production Options
To determine which options are the best for your organisation you will need consider a range
of financial and non-financial considerations associated with each.
Financial Considerations
To help determine the company鈥檚 financial ability to implement each option and its economic
viability. Once you have a short list of possible option you can use the following table to
evaluate them. Consider:
鈥? the cost and benefits of each option
鈥? the capital investment required; and
鈥? the payback period.
CP Option Example Value
1) 2) 3)
(e.g. Optimise
(e.g. Upgrade
furnace)
furnace)
Equipment
Capital Costs
Installation
Maintenance
Annual Costs
Materials
Total Costs
Increased Sales
Benefits
Sale of By-products
Annual Savings:
Materials
Water
Energy
Treatment
Disposal
Total Benefits
Net Annual
Benefits
Payback Period
Self Assessment Checklists 16
CLEANER PRODUCTION
SELF ASSESSMENT GUIDE
Other Considerations
As well as financial options, you also need to consider how the change will impact on your
other systems and the practical implementation issues associated with each option.
Non-Economic Analysis
Questions Notes Likely
(sources, causes, potential Impact
improvements) (1-5)
How will the change affect product
quality (positive/negative)? Are any
trade-offs acceptable?
How will the change affect health
and safety (positive/negative)?
What are your customers
expectations? Would they care
about the change? What changes
would they accept or even find
desirable?
What impact will the change have
on the environmental performance
of the company (i.e. reduce the
toxicity or impact of wastes, reduce
environmental liability etc.)?
What are the requirements of
people in different departments (i.e.
purchasing, cleaning, production,
maintenance)? What is the best
compromise solution?
How easy will it be to implement
the change? How much time, and
expertise will be needed? Are these
resources readily available?
Self Assessment Checklists 17
Cleaner Production Manual for the Queensland Foundry Industry November 1999
PART 5: OVERVIEW OF FOUNDRY PROCESSES
Contents
1. Overview of Casting Processes...................................................................... 3
2. Casting Processes.......................................................................................... 6
2.1 Sand Casting ............................................................................................ 6
2.1.1 Pattern Making ................................................................................... 7
2.1.2 Mould Making ..................................................................................... 7
2.1.3 Melting and Pouring ........................................................................... 8
2.1.4 Cooling and Shakeout ........................................................................ 9
2.1.5 Sand Reclamation .............................................................................. 9
2.1.6 Fettling, Cleaning and Finishing....................................................... 10
2.1.7 Advantages of Sand Casting ............................................................ 10
2.1.8 Limitations ........................................................................................ 10
2.1.9 By-products Generated .................................................................... 10
2.2 Shell Moulding ........................................................................................ 13
2.2.1 Advantages....................................................................................... 13
2.2.2 Limitations ........................................................................................ 14
2.2.3 By-products Generated .................................................................... 14
2.3 Investment Casting ................................................................................. 15
2.3.1 Advantages....................................................................................... 16
2.3.2 Limitations ........................................................................................ 16
2.3.3 By-products Generated .................................................................... 17
2.4 Lost Foam Casting .................................................................................. 18
2.4.1 Advantages....................................................................................... 19
2.4.2 Limitations ........................................................................................ 19
2.4.3 By-products Generated .................................................................... 20
2.5 Die Casting ............................................................................................. 21
2.5.1 Advantages....................................................................................... 21
2.5.2 Limitations ........................................................................................ 22
2.5.3 By-products Generated .................................................................... 22
2.6 Special and Innovative Moulding and Casting Processes ...................... 23
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.7 The Hitchiner Process............................................................................. 23
2.7.1 Advantages....................................................................................... 23
2.7.2 Limitations ........................................................................................ 23
2.8 The Shaw Process .................................................................................. 24
2.8.1 Advantages....................................................................................... 24
2.8.2 Limitations ........................................................................................ 24
2.9 Replicast庐............................................................................................... 24
2.9.1 Advantages....................................................................................... 24
2.9.2 Limitations ........................................................................................ 25
2.10 Vacuum (鈥榁鈥?) Process............................................................................ 25
2.10.1 Advantages..................................................................................... 25
2.10.2 Limitations ...................................................................................... 26
2.11 Centrifugal Casting ............................................................................... 26
2.11.1 Advantages..................................................................................... 26
2.11.2 Limitations ...................................................................................... 26
2.12 Cosworth Process ................................................................................. 26
2.12.1 Advantages..................................................................................... 27
2.12.2 Limitations ...................................................................................... 28
2.13 Semi-Solid Metal Casting Process........................................................ 28
2.13.1 Advantages..................................................................................... 28
2.13.2 Limitations ...................................................................................... 28
3. Melting Technology ...................................................................................... 29
3.1 Cupola Furnaces..................................................................................... 29
3.2 Electric Induction Furnaces..................................................................... 32
3.3 Electric Arc Furnaces.............................................................................. 34
3.4 Rotating Furnaces................................................................................... 35
3.5 Crucible Furnaces................................................................................... 36
3.6 Environmental Issues.............................................................................. 36
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
1. Overview of Casting Processes
This section provides a brief description of the major casting processes, for the
benefit of readers who are unfamiliar with the industry. Metal casting involves
pouring molten metal into a mould containing a cavity of the desired shape to
produce a metal product. The casting is then removed from the mould and
excess metal is removed, often using shot blasting, grinding or welding
processes. The product may then undergo a range of processes such as heat
treatment, polishing and surface coating or finishing.
The casting techniques described in this section are variations of the process
described in the previous paragraph. The different techniques have been
designed to overcome specific casting problems or to optimise the process for
specific metals, product designs and scales or other operational considerations
such as automation.
All casing processes use a mould, either permanent or temporary, which is a
鈥榥egative鈥? of the desired shape. Once the metal is poured and has solidified it
forms the 鈥榩ositive鈥? shape of the desired product. Processes differ in the
number of stages that are required to produce the final casting. Die casting is
the simplest technique in terms of the number of stages used. The process
uses a permanent mould (-ve) to produce the final casting (+ve). Processes,
such as sand moulding and shell casting, use a temporary mould (-ve) which is
typically produced using a permanent pattern or die (+ve). Investment casting
and lost foam casting techniques use a temporary mould (-ve) that is build
around a temporary pattern (+ve). For repetitive work, patterns are often
produced using a permanent mould or die (-ve). Table 1 summarises the
patterns and moulds typically used for these five common casting techniques.
Table 1: Types of Patterns and Moulds Used in the
Major Casting Techniques
Die casting Sand casting Shell casting Investment
casting and lost
foam casting
Permanent die Permanent pattern Permanent pattern Permanent die
(optional)
-ve shape +ve shape +ve shape
-ve shape
Temporary pattern
+ve shape
Temporary mould Temporary mould Temporary mould
-ve shape -ve shape -ve shape
Final casting Final casting Final casting Final casting
+ve shape +ve shape +ve shape +ve shape
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
For die casting, the die is typically made of a high-strength metal or graphite
material and is expensive to produce. This process, therefore, is most suited to
repetitive and high-value casting (Luther, 1999). Sand casting is the most
common technique used in Australia and around the world. The process
combines good casting quality with flexibility in metal type and casting size.
This process is most suited to jobbing foundries that produce a wide variety of
products, and for large castings. Permanent patterns are typically made out of
wood so are less expensive than die moulds. This pattern is used to make a
temporary or destroyable mould out of sand. Metal is poured into the mould,
which collapses once the casting has hardened.
The shell casting process was developed to achieve high levels of throughput
for repetitive casting operations. The sand:metal ratio is greatly reduced and
the dimensional accuracy of the castings is typically higher than for sand
moulding, reducing the work involved in cleaning and machining the product.
This process is good for routine work but lacks the flexibility of sand moulding,
and the size of castings is restricted.
In investment casting and lost foam casting, temporary patterns are made from
wax or foam. These patterns can be produced manually using traditional
carving tools, carved mechanically using automated tooling, or, for high-volume
castings, they can be produced using permanent moulds or dies. These
processes are more expensive and limited in terms of casting size but achieve
the highest casting quality. Investment casting can be very cost effective for
producing complex geometries that would be difficult or impossible to machine.
Lost foam also achieves high dimensional accuracy and has many
environmental and operation benefits over traditional sand casting.
No casting process is inherently the best. Therefore companies need to select
the most appropriate technique or techniques that suit the type of castings
produced and the operational constraints. The major casting methods and their
more common variants are discussed in the sections that follow. A general
comparison of the four main methods is provided in Table 2.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Table 2: Comparison of Several Casting Methods
Sand Die casting Sand鈥搒hell Investment
casting casting
Low High Average Average
Tool costs
Average Low Average High
Unit costs
over 1 tonne 30 kg 100 kg 45 kg
Maximum
casting weight
2.5 0.8 2.5 1.6
Thinnest
section
castable (mm)
0.3 0.25 0.25 0.25
Typical
dimensional
tolerance (mm)
Fair to good Best Good Very good
Relative
surface finish
Good Very good Good Fair
Relative
mechanical
properties
Fair to good Good Good Best
Relative ease
of casting
complex
designs
Best Poorest Fair Fair
Relative ease
of changing
design in
production
Most Low Average High
Metal options
Note: Actual casting characteristics vary depending upon the metal uses,
casting geometry and other factors.
Sources: USEPA (1998) and Hitchener (1999)
Page 5
Cleaner Production Manual for the Queensland Foundry Industry November 1999
2. Casting Processes
2.1 Sand Casting
Sand casting is the most common technique used in Australia, as it is around
the world. A generalised process flow diagram of a typical sand casting process
is shown in Figure 1.
Figure 1: A Typical Sand Casting Process
Ingots and New sand
alloys
Sand
Pour
Metal Mould
Binder
Fuel
Cooling
Cores
Additives
Furnace
Flux/additives Sand mixer
Shakeout
Sand reclamation
Castings
Fettling
Scrap
Off-site
Cleaning
scrap Heat treatment
(optional)
Inspection
Finishing
Finished casting
Source: Environment Canada (1997)
Sand moulding systems use sand as a refractory material and a binder that
maintains the shape of the mould during pouring. A wide range of sand/binder
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
systems are used. Green (wet) sand systems, the most common sand system,
use bentonite clay as the binder, which typically makes up between 4%
and10% of the sand mixture. Water, which makes up around 2鈥?4% of the sand
mixture, activates the binder. Carbonaceous material such as charcoal (2鈥?10%
of total volume) is also added to the mixture to provide a reducing environment.
This stops the metal from oxidising during the pouring process. Sand typically
comprises the remaining 85鈥?95% of the total mixture (Environment Canada,
1997).
Other sand moulding processes utilise a range of chemical binders. Oil binders
are combinations of vegetable or animal oils and petrochemicals. Typical
synthetic resin binders include phenolics, phenolformaldehyde, urea-
formaldehyde, urea-formaldehyde/furfuryl alcohol, phenolic isocyanate, and
alkyl isocyanate. Chemical resin binders are frequently used for foundry cores
and less extensively for foundry moulds (Environment Canada, 1997).
2.1.1 Pattern Making
Pattern making is the first stage for developing a new casting. The pattern, or
replica of the finished piece, is typically constructed from wood but may also be
made of metal, plastic, plaster or other suitable materials. These patterns are
permanent so can be used to form a number of moulds. Pattern making is a
highly skilled and precise process that is critical to the quality of the final
product. Many modern pattern shops make use of computer-aided design
(CAD) to design patterns. These systems can also be integrated with
automated cutting tools that are controlled with computer-aided manufacturing
(CAM) tools (USEPA, 1998). Cores are produced in conjunction with the
pattern to form the interior surfaces of the casting. These are produced in a
core box, which is essentially a permanent mould that is developed (USEPA,
1998).
2.1.2 Mould Making
The mould is formed in a mould box (flask), which is typically constructed in two
halves to assist in removing the pattern. Sand moulds are temporary so a new
mould must be formed for each individual casting. A cross-section of a typical
two-part sand mould is shown in Figure 2.
The bottom half of the mould (the drag) is formed on a moulding board. Cores
require greater strength to hold their form during pouring. Dimensional
precision also needs to be greater because interior surfaces are more difficult
to machine, making errors costly to fix. Cores are formed using one of the
chemical binding systems (Environment Canada, 1997). Once the core is
inserted, the top half of the mould (the cope) is placed on top. The interface
between the two mould halves is called a parting line. Weights may be placed
on the cope to help secure the two halves together, particularly for metals that
expand during cooling (USEPA, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Figure 2: Cross-section of a typical two-part
sand mould
Mould
Pouring Cup box (flask)
COPE
Sprue
Riser Core
Gating
Parting Mould
system
line cavity
DRAG
Source: Adapted from Hurst (1996)
Mould designs include a gating system which is designed to carry molten metal
smoothly to all parts of the mould. The gating system typically includes a sprue,
gates, runners and risers. The sprue is where the metal is poured. Gates allow
the metal to enter the running system. Runners carry the molten metal towards
the casting cavity. Risers may have several functions including vents to allow
gases to be released, reservoirs prior to the casting cavity to aid progressive
solidification, and waste cavities to allow metal to rise from the casting cavity to
ensure it is filled and to remove the first poured metal from the casting cavity,
thus avoiding solidification problems (Hurst, 1996).
2.1.3 Melting and Pouring
Many foundries, particularly ferrous foundries, use a high proportion of scrap
metal to make up a charge. As such, foundries play an important role in the
metal recycling industry. Internally generated scrap from runners and risers, as
well as reject product, is also recycled. The charge is weighed and introduced
to the furnace. Alloys and other materials are added to the charge to produce
the desired melt. In some operations the charge may be preheated, often using
waste heat. The furnaces commonly used in the industry are described below.
In traditional processes metal is superheated in the furnace. Molten metal is
transferred from the furnace to a ladle and held until it reaches the desired
pouring temperature. The molten metal is poured into the mould and allowed to
solidify (USEPA, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.1.4 Cooling and Shakeout
Once the metal has been poured, the mould is transported to a cooling area.
The casting needs to cool, often overnight for ambient cooling, before it can be
removed from the mould. Castings may be removed manually or using vibratory
tables that shake the refractory material away from the casting.
Quenching baths are also used in some foundries to achieve rapid cooling of
castings. This speeds up the process and also helps achieve certain
metallurgical properties. The quench bath may contain chemical additives to
prevent oxidation (USEPA, 1998).
2.1.5 Sand Reclamation
Most sand foundries recover a significant proportion of the waste sand for
internal reuse. This significantly reduces the quantity of sand that must be
purchased and disposed of. In Queensland, most sand is reclaimed
mechanically; cores and large metal lumps are removed by vibrating screens
and the binders are removed by attrition (i.e. by the sand particles rubbing
together). Fine sand and binders are removed by extraction and collected in a
baghouse. In some systems metals are removed using magnets or other
separation techniques. For operations using mechanical reclamation, the
recycle rate is often limited to around 70%. This is due to the need to maintain
a minimum sand quality. For large iron foundries, where sand quality
requirements are less stringent, over 90% reclamation can be achieved by
mechanical means . For many processes, mechanically reclaimed sand is not
of sufficiently high quality to be used for core production.
Thermal reclamation is becoming more widely used in Queensland. This
process heats the sand to the point where organic materials, including the
binders, are driven off. This process can return the sand to an 鈥榓s new鈥? state,
allowing it to be used for core making. Thermal reclamation is more expensive
than mechanical systems.
Sand can also be reclaimed using wet washing and scrubbing techniques.
These methods produce sand of a high quality but are not commonly used
because they generate a significant liquid waste stream and require additional
energy input for sand drying.
The amount of internal reuse depends on the type of technology used and the
quality requirements of the casting process. Reclamation processes,
particularly mechanical ones, break down the sand particles and this can affect
the quality of some metals. Also, for mechanical reclamation techniques,
impurities may build up in the sand over time, requiring a proportion of the
material to be wasted. Large iron foundries do not require a high sand quality
so typically achieve the highest rate of reuse in the industry. Often sand cycles
through the operation until it is ground down to a fine dust and removed by
baghouses.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.1.6 Fettling, Cleaning and Finishing
After the casting has cooled, the gating system is removed, often using
bandsaws, abrasive cut-off wheels or electrical cut-off devices. A 鈥榩arting line
flash鈥? is typically formed on the casting and must be removed by grinding or
with chipping hammers. Castings may also need to be repaired by welding,
brazing or soldering to eliminate defects (Environment Canada, 1997).
Shot blasting 鈥? propelling abrasive material at high velocity onto the casting
surface 鈥? is often used to remove any remaining metal flash, refractory
material or oxides. Depending on the type and strength of the metal cast, the
grade of shot may vary from steel ball bearings to a fine grit (Environment
Canada, 1997).
The casting may undergo additional grinding and polishing to achieve the
desired surface quality. The casting may then be coated using either a paint or
a metal finishing operation such as galvanising, powder coating or
electroplating.
2.1.7 Advantages of Sand Casting
鈥? Use is widespread; technology well developed.
鈥? Materials are inexpensive, capable of holding detail and resist deformation
when heated.
鈥? Process is suitable for both ferrous and non-ferrous metal castings.
鈥? Handles a more diverse range of products than any other casting method.
鈥? Produces both small precision castings and large castings of up to 1 tonne.
鈥? Can achieve very close tolerances if uniform compaction is achieved.
鈥? Mould preparation time is relatively short in comparison to many other
processes.
鈥? The relative simplicity of the process makes it ideally suited to
mechanisation.
鈥? High levels of sand reuse are achievable (USEPA, 1998).
2.1.8 Limitations
鈥? Typically limited to one or a small number of moulds per box..
鈥? Sand:metal ratio is relatively high.
鈥? High level of waste is typically generated, particularly sand, baghouse dust
and spent shot.
2.1.9 By-products Generated
Foundries are often perceived as being dirty and environmentally unfriendly.
However, most modern foundries are relatively environmentally benign in
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comparison to other industrial activities in the metal sector (e.g. smelting and
surface finishing), and most of the by-products generated by the industry have
relatively low impacts. The major issues facing the industry are the large
volumes of by-products that are currently being sent to landfill, nuisance
odours, and the need to maximise health and safety in the industry.
Sand is the largest by-product generated by volume in this process. Even in
operations that undertake a high level of reclamation, some new sand is
required to maintain the quality of the sand in the system. As a result some
sand is lost from the system. This may be sent to landfill, reclaimed off-site or
put to beneficial reuse.
Foundry sands from ferrous foundries are not usually considered to be
hazardous, typically passing TCLP (toxic characteristic leaching procedure)
tests, and can be sent to unlined landfill. Some non-ferrous sands contain high
quantities of heavy metal, which requires them to be sent to secured landfill
sites. Most of the chemical binder used in core and mould making is burnt off
during the pouring process. Binders in waste sand can become an important
issue if large volumes of resin-coated sands are wasted before the pouring
stage. Binders and salts can build up to unacceptable levels over many
reclamation cycles, so careful monitoring and testing is important.
Baghouse dust from the mould and core shops and from the shotblasting
operations is typically the second largest by-product generated by volume in
sand casting processes. Sand grains are broken down into fines and dust,
particularly after multiple reuse, and this can affect casting quality and also
create occupational health and safety issues (e.g. silicosis). Many foundries
have invested in baghouses to capture sand dusts and other particulate matter
from the working environment and from reclamation processes.
Slag is another significant by-product stream by volume. Flux is a material
added to the furnace charge or to the molten metal to remove impurities. Flux
unites with impurities to form dross or slag This rises to the surface of the
molten metal, from where it is removed before pouring. When cooled this forms
a relatively inert complex glass-like structure which can usually be disposed of
in unlined landfill or put to beneficial reuse.
Other solid wastes generated in sand casting operations include:
鈥? refractories (furnace and ladle lining);
鈥? drums;
鈥? spent shot;
鈥? metal swarf and shavings;
鈥? timber pallets and timber from the pattern room;
鈥? general foundry waste including packaging and consumables (e.g. rags,
gloves, grinding wheels etc).;
鈥? general office and lunchroom wastes.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
These materials typically make up a minor proportion of the total waste stream
by volume, but can be significant in terms of cost. Timber pallets are a
significant issue at a number of Queensland foundries.
Foundries also produce small quantities of liquid by-product streams. The
major sources are cutting fluids, hydraulic and other oils, solvents, waste paints
and paint sludges, uncured and cured binders and waste catalysts (acids and
bases). Water streams are also generated from quenching baths, cooling
systems and other minor sources.
Air emissions from the process typically include carbon monoxide, organic
compounds, hydrogen sulfide, sulfur dioxide, nitrous oxide, benzene, phenols,
and other hazardous air pollutants (HAPs). The actual emissions depend on a
number of factors including the type of metal poured, the cleanliness of the
charge, the types of binders used and the melting and pouring practices
employed. A portion of the metal (around 3%) volatilises during the melting and
pouring process. The major environmental issues related to these fugitive
emissions are usually those of occupational health within the foundry and
nuisance odours outside the foundry (USEPA, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.2 Shell Moulding
Shell moulding is a process well suited to rapid,
Pattern heating
automated, repetitive and high-volume production.
Heat
The most common method for producing shell
Pattern
moulds is to use a dump box as shown in the
Plate
diagram. The dump box is rotated through 3600 so
Heat that the sand contacts the heated surface. An
organic thermosetting resin such as phenol
Coating
formaldehyde or furane is typically used (2.5鈥?4.5%
Dump box
of sand volume) in conjunction with a catalyst (11鈥?
14% of resin volume). Catalysts include weak
Sand
aqueous acids such as ammonium chloride or
hexamine, a white powder (Brown (1994) and
Curing UNEP (1997).
Heat
The thickness of the shell, typically around 10 mm,
is determined by the contact time between the
sand and pattern (Clegg, 1991). The mould is
heated again to cure the sand, causing it to
Heat
harden. The mould is released from the pattern
Ejection using ejector pins. The entire cycle can be
completed in a matter seconds, making it suitable
for rapid production.
Cores are added to the mould and the two halves
of the mould are glued and clamped together
before the metal is poured.
Ejectors
Moulds are relatively robust and can therefore be
Joining stored for reasonably long periods of time (Luther,
1999). Depending on the cores used, spent sand
can be reclaimed successfully using thermal
Pin Core
Clamps
reclamation (Brown, 1994).
2.2.1 Advantages
Glue
鈥? Good casting detail and dimensional accuracy
are possible.
Pouring and knockout
鈥? Moulds are lightweight and may be stored for
extended periods of time.
鈥? Gives superior surface finish and higher
dimensional accuracy, and incurs lower fettling
costs than conventional sand castings.
鈥? Has better flexibility in design than die-casting.
鈥?
Source: Adapted from Is less expensive than investment casting.
Clegg (1991)
鈥? Capital plant costs are lower than for
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
mechanised green sand moulding.
鈥? Metal yields are relatively high.
鈥? Sand:metal ratios are relatively low (Luther (1999) and Clegg (1991)).
2.2.2 Limitations
鈥? The weight of castings is limited to 100 kg.
鈥? Because the process requires heat to cure the mould, pattern costs and
pattern wear can be higher than for conventional sand moulding.
鈥? Energy costs also tend to be higher.
鈥? Sand inputs need to be of higher quality than traditional sand casting.
鈥? Emissions from the process are noxious, so effective extraction systems are
required.
鈥? Material costs tend to be higher than those for conventional sand moulding
(Luther (1999) and Clegg (1991)).
2.2.3 By-products Generated
Significantly less sand is required to make a shell mould than to make a
conventional sand mould, so volumes of spent sand are typically smaller.
Quantities of binder per tonne of metal are also smaller. Most of the binder is
burnt off in the pouring process, so only minor amounts remain in the sand.
Broken cores and sand that has set up prematurely or inadequately may have
higher levels of resin (UNEP, 1997).
The burnt-off resins create nuisance odour issues for staff and neighbours.
Dust emissions are also created in the moulding, handling and sand
reclamation processes. If the moulds are water cooled, wastewater may contain
traces of metals, phenols, furans and other contaminants, depending on the
binder system used (UNEP (1997) and Brown (1994)).
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2.3 Investment Casting
Investment casting produces very high surface
Pattern making
quality and dimensional accuracy. It is commonly
used for precision equipment such as surgical
equipment, for complex geometries and for
precious metals. This process is commonly used
by artisans to produce highly detailed artwork.
Gating The first step is to produce a pattern or replica of
the finished mould. Wax is most commonly used to
form the pattern, although plastic is also used.
Patterns are typically mass-produced by injecting
liquid or semi-liquid wax into a permanent die
(USEPA, 1998). Prototypes, small production runs
Shell pattern formation and specialty projects can also be undertaken by
carving wax models. Cores are typically
unnecessary but can be used for complex internal
structures. Rapid prototyping techniques have
been developed to produce expendable patterns.
Several replicas are often attached to a gating
system constructed of the same material to form a
tree assembly. In this way multiple castings can be
produced in a single pouring (Jain, 1986).
Wax removal
The next stage is to create a one-piece
destroyable mould around the pattern (USEPA,
1998). This mould is built up around the wax
pattern in stages by alternately coating the
assembly with a specially formulated heat-resistant
refractory slurry mixture and then applying a
granulated refractory 鈥榮tucco鈥? shell (Jain, 1986).
Pouring The initial coats use a fine powder, which creates a
very smooth and dimensionally accurate negative
of the pattern. Subsequent coats use a coarser
refractory material to build up sufficient thickness.
This material hardens around the assembly at
room temperature. This investment shell casting
method is the more common process. An
alternative process is to use an investment flask,
Knockout where sand is packed around the mould. This can
be desirable where additional mould strength is
required and also allows the casting size to be
increased.
In both shell and flask casting, the pattern is
Source: Adapted from removed from the mould prior to the pouring stage.
Jain (1986) The mould is inverted and heated to melt and
remove the wax (Jain, 1986). In some operations
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
the melted wax is recovered and reused to make new patterns (USEPA, 1998).
After multiple reuses the material needs to be reconditioned to maintain its
purity, or disposed of.
The mould is then heated in an oven to remove any residual wax and to further
cure and harden the mould. The temperature is raised to 980oC prior to
pouring. This is a time- and energy-consuming process: total heating time, from
wax removal to pouring, can take up to 15 hours (Jain, 1986).
Molten metal is then poured into the central cavity and flows into the individual
moulds (USEPA, 1998). After the metal has cooled, the mould material is
removed.
Because of its very high dimensional accuracy the process can achieve a net-
shape cast requiring little or no machining. Great care is taken in the pattern-
making stage to remove any mould lines because it is more cost effective to
remove unwanted material from the wax model than from the final cast.
2.3.1 Advantages
鈥? There is very high dimensional accuracy and surface finish.
鈥? Process is suitable for both ferrous and non-ferrous precision pieces.
鈥? Allows flexibility of design.
鈥? The process can be adapted for mass production.
鈥? Cores are typically eliminated.
鈥? Can virtually eliminate the need for machining.
鈥? Very high metal yields.
鈥? Can produce castings that are impossible or difficult to produce with other
casting methods and machining processes.
鈥? Can be cost effective for repetitive casting and specialist jobbing
applications (Luther (1999); Jain (1986); and USEPA (1998)).
2.3.2 Limitations
鈥? The size of castings is limited (up to around 5 kg).
鈥? Capital and operating costs are high in comparison with other casting
methods.
鈥? Costs of pattern die-making are high, requiring special tooling and
equipment.
鈥? There are numerous steps in the process, making automation somewhat
more difficult and more expensive than for other casting methods.
鈥? Casting costs make it important to take full advantage of the process to
eliminate all machining operations (Luther (1999); Jain (1986); and USEPA
(1998)).
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2.3.3 By-products Generated
The volume of by-product material produced from the investment casting
process are small in comparison to sand casting techniques but larger than for
die casting. Waste refractory mould material and waxes (or plastic) represent
the largest volume of by-products generated. Investment casting refractory
material can be used only once and can be disposed of in unsecured landfill
unless it contains high levels of heavy metals. Wax can be reused a number of
times before it has to be reconditioned, thus minimising waste. Small losses of
wax occur when the moulds are cured and this creates some odours. Odours
from the process are relatively low, however, and air emissions comprise
mostly particulate matter. Dusts generated from the process contain metal
which, in sufficiently high quantities, can be reclaimed economically (USEPA,
1998).
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2.4 Lost Foam Casting
The lost foam or expendable pattern-casting process is
a relatively new process in commercial terms, but is
gaining increased attention due to the environmental
and technical benefits that are achievable for some
types of casts. In this process, an expendable pattern
Pattern making is formed out of polystyrene foam. Patterns can be
made manually, using automated systems or by
moulding them using a permanent die.
Manual pattern making typically involves carving
blocks and gluing sections together to build up the
desired shape. The finished pattern is a single piece
(i.e. no cores) incorporating all necessary gating
Mould making systems. This carving process can be automated using
computer-aided manufacturing (CAM) system sand can
incorporate rapid prototyping techniques.
For repetitive castings, patterns can be moulded using
a permanent aluminium die. Polystyrene beads are
pre-expanded using a vacuum, steam or hot air
processes. This helps to minimised the density of the
foam as much as possible, to minimise the amount of
Pouring
vapour that is produced during the pouring process.
The expanded material is then blown into the
aluminium mould. Steam is used to cause the material
to expand further, bond together and fill the mould
cavity. The mould and pattern are allowed to cool, and
the pattern ejected (USEPA, 1998).
As for investment casting, when the casting is small,
multiple castings can be joined, often to a central tree,
to increase pouring efficiency.
Cleaning
The pattern is coated with a specially formulated gas-
permeable refractory slurry (USEPA, 1998). When the
refractory slurry has hardened, the assembly is
positioned in a flask, and unbonded sand is poured
around the mould and compacted into any internal
cavities. The refractory coating must be sufficiently
strong to prevent the loose sand from collapsing into
Source: Adapted from the cavity as the pattern vaporises, but also permeable
USEPA (1998) to allow styrene vapour to escape from the mould
cavity (USEPA, 1998). A vacuum system can also be
used to increase sand compaction.
Molten metal is then poured into the polystyrene
pattern, which vaporises and is replaced by the metal.
This is different from the lost wax process in which the
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
wax is removed before the pouring stage. Vents in the side of the flask allow
vapour to escape. If vapour is produced more rapidly than it can be vented, the
casting may become deformed. When the metal has solidified, the flask is
emptied onto a steel grate for shakeout. The loose sand falls through the grate
and can be reused without treatment. The refractory material is broken away
from the casting in the usual manner (USEPA, 1998).
2.4.1 Advantages
鈥? Can be used for precision castings of ferrous and non-ferrous metals of any
size.
鈥? Fewer steps are involved in lost foam casting compared to sand casting.
鈥? Coremaking is eliminated.
鈥? Binders or other additives and related mixing processes are eliminated.
鈥? High dimensional accuracy can be achieved and thin sections can be cast
(i.e. 3 mm).
鈥? There is lower capital investment.
鈥? The flasks used are less expensive and easier to use because they are in
one piece.
鈥? The need for skilled labour is reduced.
鈥? Multiple castings can be combined in one mould to increase pouring
efficiency.
鈥? Lower operating costs can be achieved for appropriate castings. Complex
castings, particularly internal sections, which require high dimensional
accuracy and have thin sections, can be produced very cost effectively in
comparison with to conventional sand moulding processes.
鈥? Fettling and machining is minimised due to high dimensional accuracy and
the absence of parting lines or core fins.
鈥? The shakeout process is simplified and does not require the heavy
machinery required for bonded sand systems.
鈥? High levels of sand reuse are possible. As little as 1鈥?2% of the sand is lost
as a result of spills. Periodically a portion of sand may need to be removed
or reclaimed to avoid the build-up of styrene (Luther, 1999).
2.4.2 Limitations
鈥? The pattern coating process is time-consuming, and pattern handling
requires great care.
鈥? Very thin sections can be flimsy, making dimensional accuracy difficult to
maintain during sand compaction.
鈥? Good process control is required as a scrapped casting means replacement
not only of the mould but of the pattern as well.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? For simple casings and for jobbing processes, the process is typically not
competitive against conventional sand moulding.
鈥? With the exception of aluminium and grey and ductile iron, experience with
other metals is limited.
鈥? There are some limitations in using the technique to cast low-carbon alloys
(Luther (1999) and USEPA (1998)).
2.4.3 By-products Generated
Lost foam is considered to be a cleaner process than many other casting
processes due to the elimination of binders. The large quantities of polystyrene
vapours produced during lost foam casting, however, can be flammable and
may contain hazardous air pollutants. Large volumes of waste foam can be
generated from carving operations. This can be a significant cost, particularly
for companies that pay by volume and not by weight. Other possible air
emissions are of particulate matter related to the use of sand. Waste sand and
refractory materials containing styrene may also be generated (USEPA, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.5 Die Casting
Die casting is a precision casting technique that uses a
permanent metal mould, or die, into which molten metal
is poured directly. Metal is typically forced into the
mould under pressure but gravity-feed systems are
also used. Tooling costs and other capital costs are
Die making
high due to the cost of designing dies. Operational
costs, however, are relatively low, due to the high level
of automation and the small number of production
steps (i.e. direct pouring into a permanent mould rather
than preparing destroyable patterns and/or moulds).
The process, therefore, is best suited to mass
production.
Casting assembly
Die casting is most suitable for non-ferrous metals with
Moving
Fixed relatively low melting points (i.e. around 870oC) such
plate
plate
as lead, zinc, aluminium, magnesium and some copper
alloys (Luther, 1999). Casing metals with high melting
points, including iron, steel and other ferrous metals,
reduces die life (Clegg, 1991).
Dies are usually made from two blocks of steel, each
containing part of the cavity, which are locked together
Metal injection and
while the casting is being made. Retractable and
pressing
removable cores are used to form internal surfaces.
Molten metal is injected into the die and held under
pressure until it cools and solidifies. The die halves are
then opened and the casting is removed, usually by
means of an automatic ejection system.
The die is cleaned between each casting cycle,
preheated and lubricated to reduce wear on the die, to
improve surface quality and to aid ejection. Mould
Release coating material can also be used to protect the molten
metal from the relatively cool and conductive surface of
the mould. Cooling systems are often used to maintain
the desired operating temperature (USEPA, 1998).
2.5.1 Advantages
鈥? Once capital is in place, operating costs are low
relative to most other casting processes. This is
Source: Adapted from
due to the reduced number of process steps, the
Clegg (1991)
elimination of temporary moulds and patterns from
the process, and the lower volume of materials that
need to be handled.
鈥? Dies can sustain very high production rates (i.e.
over 400 shots per hour). Total cost of castings can
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
be relatively low at high levels of production.
鈥? High design flexibility and complexity allows products to be manufactured
from a single casting instead of from an assembly of cast components.
鈥? Good accuracy, consistency and surface finish are possible, with high metal
yields.
鈥? Cleaning, machining, finishing and fabrication costs are low.
鈥? There are low levels of waste due to elimination of refractory material
,leading to a cleaner work environment.
2.5.2 Limitations
鈥? Capital costs for equipment and dies are high.
鈥? Pressure dies are very expensive to design and produce.
鈥? Die casting is not applicable to steel and high-melting-point alloys.
鈥? Casting size is limited to a maximum of about 35 kg (Luther (1999) and
USEPA (1998)).
2.5.3 By-products Generated
This process generates the smallest volumes of waste of all foundry processes
because the use of refractory sands and binders for moulds is eliminated.
Fettling is minimised, so only small volumes of swarf and consumables are
generated in the grinding and cleaning process.
Some air emissions are released during the melting and casting process. Metal
oxide fumes are released as some of the metal vaporises and condenses. The
lubricants used also vaporise on contact with the molten metal (USEPA, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.6 Special and Innovative Moulding and Casting
Processes
The basic techniques described above have all been adapted in various ways
to optimise them for specific metals and operational considerations. This
section describes some of the major innovations that have been developed
from the basic processes.
2.7 The Hitchiner Process
The Hitchiner casting process is a variation of chemically bonded sand
moulding processes. It uses a counter-gravity (vacuum) system to fill the mould
cavity with molten metal. The flask is partially submerged in a metal bath. Small
diameter feeders in the drag (bottom) half of the flask are used to draw metal
under vacuum into the mould cavity (Luther, 1999).
Filling moulds by gravity (i.e. by pouring into a sprue) can introduce air into the
mould cavity and result in defects. Introduced air can constitute up to 30% of
the total volume of metal poured (MCTC, 1995). The Hitchener process
achieves better filling consistency and virtually eliminates air ingress and the
resulting inclusions and porosity defects. This has been shown to reduce
casting repair costs by 50鈥?65% (MCTC, 1995). Such cost savings can
compensate for the higher up-front costs.
2.7.1 Advantages
鈥? Produces light section castings in a variety of alloys normally not castable
by other processes.
鈥? Gives higher casting definition than conventional sand moulding and similar
definition to investment casting.
鈥? Requires less metal cleaning.
鈥? Higher metal yields are achieved than by conventional sand moulding due
to smaller gating systems and greater precision.
鈥? Decomposition gases are removed by the vacuum, making emission control
easier, reducing emissions and reducing gas inclusions (Luther, 1999).
2.7.2 Limitations
鈥? The process is more expensive than conventional sand casting.
鈥? Production volumes are limited to low to medium throughput.
鈥? The size of the casting is limited to a maximum of 45 kg (Luther, 1999).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
2.8 The Shaw Process
The Shaw Process is one of more common variations on the investment casting
process. It is designed to eliminate the use of expendable patterns 鈥? one of
the most costly and time-consuming steps in the casting process. A refractory
slurry containing ethyl silicate is used, which initially cures to a flexible gel but
can be removed from the pattern in two halves. The flexible mould halves can
then be further cured at high temperatures until a hard mould is formed ready
for assembly and pouring (USEPA, 1998).
This process is used in Australia by Shaw Process Castings Pty Ltd. in
Mortdale, New South Wales.
2.8.1 Advantages
鈥? The process eliminates the need for expendable patterns.
2.8.2 Limitations
鈥? It is more expensive than the conventional investment process.
2.9 Replicast庐
Replicast庐 is a novel precision moulding and casting process that combines
many of the advantages of investment casting and lost foam casting
techniques. An expanded polystyrene pattern is produced and coated with an
inert, fired ceramic mould. The polystyrene is fully burnt out of the mould before
casting. This allows a wider range of alloys to be cast in the mould. Because
the foam is 92% carbon by weight, the lost foam process is unsuitable for the
majority of steel alloys. By removing the foam before casting, the Replicast庐
system can be used for even ultra-low-carbon stainless steel. This process also
offers a higher weight range than is available from investment casting.
2.9.1 Advantages
鈥? Allows larger castings than are possible with investment techniques.
鈥? Full combustion of the polystyrene before casting gives an inert mould
suitable for a wider range of alloys than lost foam, including low-carbon
steels.
鈥? Air emissions are easier to control than with lost foam.
鈥? The application of a vacuum during casting allows improved fill-out of the
mould.
鈥? The support provided by the ceramic shell during casting allows large, thin
shells to be easily poured.
鈥? Sand inclusions and other sand mould-related defects can be virtually
eliminated.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? As with investment and lost foam casting, there are no cores or parting
lines, high dimensional accuracy, and excellent surface finish.
鈥? Ceramic shell does not have to be as thick as for shell casting.
2.9.2 Limitations
鈥? Is not as suitable for thin sections as the lost wax process.
鈥? It is more expensive than the lost foam process.
2.10 Vacuum (鈥榁鈥?) Process
The V-Process was invented in Japan in 1971 as an improvement on
conventional sand casting. In this process, a thin preheated sheet of plastic film
material is placed over a pattern and a vacuum is applied to draw the sheet to
the pattern contours. The flask containing the mould is then filled with dry
unbonded silica sand which is compacted by vibration. A second plastic sheet
is placed at the back of the flask and the mould is further compacted under
vacuum. With the vacuum maintained, the pattern is then removed and the two
halves of the mould are joined and secured for pouring. After the metal has
solidified, the vacuum is removed and the casting is released (Luther (1999)
and Foundry Online (1999)).
The original inventors of this proprietary process have established working
agreements on a worldwide basis so that today individually licensed foundries
using the V-process are producing castings of all sizes and shapes. These
range from thin-sectioned curtain walls in aluminium to cast iron pressure pipe
fittings, stainless steel valve bodies and massive 8-tonne ship anchors. Other
components being routinely cast include bathtubs, railroad bolsters and side
frames, machine tools, engine parts and agricultural castings. Any metal (grey,
ductile, malleable iron, various grades of steel, or aluminium and copper-base
alloys) may be poured in a V-process mould, with the possible exception of
magnesium (Luther, 1999).
2.10.1 Advantages
鈥? Gives good dimensional accuracy and surface finish with generally twice
the accuracy of sand castings.
鈥? Eliminates gas hole defects.
鈥? Pattern life is longer because there is no contact between the sand and the
pattern.
鈥? Eliminates the use of binders and minimises sand waste.
鈥? Is suitable for a wide range of casting sizes from grams to tonnes.
鈥? The process can be used for complex geometries and can be automated to
achieve greater consistency and productivity.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? It can be highly cost competitive with other casting processes (Luther (1999)
and Foundry Online (1999)).
2.10.2 Limitations
鈥? Requires plated pattern equipment.
鈥? Close synchronisation of mould and metal readiness is essential in foundry
practice.
鈥? Is not typically suitable for high rates of production.
鈥? Is not suitable for some casting geometries due to flexibility limitations of the
plastic (Luther (1999) and Foundry Online (1999)).
2.11 Centrifugal Casting
For centrifugal casting, molten metal is introduced into a mould that is rotated
during solidification. The centrifugal force improves the feed and filling
consistency achieving surface detail. This method has been specifically
adapted to the production of cylindrical parts and eliminates the need for gates,
risers and cores. The process is typically unsuitable for geometries that do not
allow a linear flow-through of metal (Luther, 1999).
2.11.1 Advantages
鈥? Centrifugal casting improves homogeneity and accuracy in special
circumstances.
鈥? Eliminates the need for gating systems (Luther, 1999).
2.11.2 Limitations
鈥? The process imposes limitations on the shape of castings, and is normally
restricted to the production of cylindrical geometric shapes (Luther, 1999).
2.12 Cosworth Process
The Cosworth process is a precision sand casting process, which was
developed in 1978 for non-ferrous casting, initially aluminium alloys, to
engineer the Cosworth engine. The mould and core-making stages are similar
to conventional sand casting, although zircon sand is used instead of silicon,
due to its greater expansion predictability. The main feature of this process is
that the metal is pumped into the mould through the base using pressure-
assisted feeding through a simplified gating system. This is shown in Figure 3
(Aalborg University, 1998).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Figure 3: The Cosworth moulding
system
Source: Aalborg University (1998)
The absence of conventional gating and feeding systems results in castings
free of porosity (due to hydrogen) and inclusions (due to alumina). These are
common in sand and gravity die casting and impair the metallurgical integrity
and mechanical properties of the casting (Clegg, 1991).
The process also eliminates a number of minor problems associated with
conventional techniques including: blowholes from chills, cores and adhesives;
inaccurately located cores and mould halves; and metallurgical inadequacies
(particularly poor hardness or strength). It also reduces fettling time. The
process was more recently extended to a number of commercial castings with
the opening of a new foundry in 1984. In 1993 the Ford Motor company
selected the Cosworth process for its Windsor, Ontario, Plant (Clegg, 1991).
The American Foundrymen鈥檚 Society has identified the Cosworth process as
being a key emerging process, needing further investigation to develop
commercial opportunities (CMC,1998).
2.12.1 Advantages
鈥? Can cast thinner sections, allowing the design of lighter, more robust
components and resulting in considerable weight saving.
鈥? Produces exceptionally high strength and ductility due to improved
metallurgical consistency during solidification.
鈥? Gives high dimensional accuracy, resulting in minimum fettling and
machining.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? Castings are pressure-tight due to the absence of porosity and inclusions.
鈥? Tooling is comparatively inexpensive.
鈥? Is suitable for medium- to high-volume production.
鈥? Gives high metal yields and high sand reclamation (Clegg, 1991).
2.12.2 Limitations
鈥? Is not suitable for a wide range of metals and casting sizes.
2.13 Semi-Solid Metal Casting Process
Semi-solid casting is a modification of the die-casting process which achieves
metallurgical benefits similar to forging. Metal billets are heated to a semi-solid
state and pressed under pressure into the die. Prior to moulding, the heated
material can be picked up and will hold its shape unsupported. Under pressure
it flows like a liquid to take the form of the die accurately, as in die casting
(WPI, 1997). This lower-energy-intensive process creates a fine and uniform
structure that is virtually free of porosity (THRUST, 1997).
In a related process called rheocasting the metal is melted and, during
solidification to a semi-solid state, its morphology is altered using mechanical,
electromagnetic or other forces to a create a fine microstructure (WPI, 1997).
2.13.1 Advantages
鈥? Gives high dimensional accuracy and metallurgical integrity.
鈥? Extends mould life and part tolerances compared with traditional die
casting, due to lower injection temperatures.
鈥? Gives higher structural integrity, quality and soundness compared with cast
parts.
鈥? Castings can be heat-treated to obtain characteristics similar to those of
permanent mould castings.
鈥? Can achieve lower costs than forging and die-moulding processes for
certain parts (WPI (1997) and THRUST (1997)).
2.13.2 Limitations
鈥? As for traditional die casting, size is generally limited (WPI (1997) and
THRUST (1997)).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
3. Melting Technology
This section provides a general overview of furnace technology most commonly
used in the foundry industry.
Energy is a major cost in all foundries. The majority of energy used is in the
melting and metal holding processes. Five types of furnaces are commonly
used to melt metal in foundries: cupola, electric arc, reverberatory, induction
and crucible. Some foundries operate more than one type of furnace and may
even transfer molten metal between furnace types in order to make use of the
best features of each (USEPA, 1998).
The choice of which furnace or furnaces to use, or the decision to change from
one type of furnace to another, is not simple but depends on a number of
factors. These include: the scale of the operation, the type of process (e.g.
repetition or jobbing), the types of metals required, the raw materials available,
the relative cost of fuels (e.g. coal, natural gas, electricity), capital,
maintenance and operational costs, and environmental requirements and
costs.
3.1 Cupola Furnaces
The use of cupola furnaces is one of the oldest processes for making cast iron
and is still among the dominant technologies in the world. In Queensland, most
of the larger foundries have replaced their cupola furnaces with more efficient
electric furnaces. Some of these foundries still maintain a cupola furnace for
specific melts or for reserve capacity.
A typical cupola furnace (see Figure 4) consists of a water-cooled vertical
cylinder which is lined with refractory material. The process is as follows:
鈥? The charge, consisting of metal, alloying ingredients, limestone, and coal
coke for fuel and carbonisation (8鈥?16% of the metal charge), is fed in
alternating layers through an opening in the cylinder.
鈥? Air enters the bottom through tuyeres extending a short distance into the
interior of the cylinder. The air inflow often contains enhanced oxygen
levels.
鈥? Coke is consumed. The hot exhaust gases rise up through the charge,
preheating it. This increases the energy efficiency of the furnace. The
charge drops and is melted.
鈥? Although air is fed into the furnace, the environment is a reducing one.
Burning of coke under reducing conditions raises the carbon content of the
metal charge to the casting specifications.
鈥? As the material is consumed, additional charges can be added to the
furnace.
鈥? A continuous flow of iron emerges from the bottom of the furnace.
Depending on the size of the furnace, the flow rate can be as high as 100
tonnes per hour. At the metal melts it is refined to some extent, which
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
removes contaminants. This makes this process more suitable than electric
furnaces for dirty charges.
鈥? A hole higher than the tap allows slag to be drawn off.
鈥? The exhaust gases emerge from the top of the cupola. Emission control
technology is used to treat the emissions to meet environmental standards.
鈥? Hinged doors at the bottom allow the furnace to be emptied when not in use
(Larsen et al. (1997); USEPA (1998); and Environment Canada (1997)).
Figure 4: A Typical Cupola Furnace
Spark arrester
Roof hood
Charging opening
Top of charging
floor
Blast pipe connection
Wind box
Tuyere box
Tap hole and spout
Slag spout
Bottom plate
Concrete foundation
Source: Abdelrahman (1999)
The cupola furnace has received a lot of negative publicity in recent years.
However, the system does have a number of inherent advantages over electric
furnaces:
鈥? It is simple and economical to operate.
鈥? A cupola is capable of accepting a wide range of materials without reducing
melt quality. Dirty, oily scrap can be melted as well as a wide range of steel
and iron. They therefore play an important role in the metal recycling
industry
鈥? Cupolas can refine the metal charge, removing impurities out of the slag.
鈥? From a life-cycle perspective, cupolas are more efficient and less harmful to
the environment than electric furnaces. This is because they derive energy
directly from coke rather than from electricity that first has to be generated.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
鈥? The continuous rather than batch process suits the demands of a repetition
foundry.
鈥? Cupolas can be used to reuse foundry by-products and to destroy other
pollutants such as VOC from the core-making area (Taft (1995); Jain
(1986); and FTJ (1996b)).
The use of elevated oxygen in cupola furnaces has been demonstrated to
increase the efficiency of the system and the quality of the melt. This use of
oxygen enrichment has progressed from simple enrichment of the blast air, to
tuyere injection, to supersonic tuyere injection. Each improvement has been
found to increase productivity by between 10% and 15% over the previous
system (FTJ, 1999a). The main benefits of elevated oxygen include:
鈥? reduced coke rate;
鈥? elevated temperature;
鈥? increased melting rate;
鈥? more consistent metal composition;
鈥? reduced waste gas emissions;
鈥? longer refractory life (FTJ, 1999a).
The migration from cupola furnaces to electric induction furnaces has resulted
from a number of factors including:
鈥? greater control over melt temperature and characteristics;
鈥? higher on-site emissions from cupolas than for electric furnaces, requiring
more expensive emission control technology;
鈥? a typically dirtier operating environment for cupolas;
鈥? less flexibility in terms of the range of alloys that can be used in cupolas;
鈥? additional environmental, storage and space issues created by on-site
storage of coke and fluxes (Abdelrahman, 1999).
Cokeless cupola furnaces have been developed more recently 鈥? over the past
20 years. These improved designs, which can be retrofitted onto existing
furnaces, achieve a number of efficiency, metallurgical and environmental
benefits over traditional cupola furnaces. First, the use of coke is eliminated. A
range of fuels including natural gas, propane, diesel oil and powdered coal can
be used. Sulfur pick-up in the melting process can be minimised (below
0.01%). Emissions, particularly of particulate material, from the system are
greatly reduced; if high-quality scrap is used emissions can be very low, thus
reducing the need for complex emission control systems. Tapped metal is
cleaner and better quality, wear of the refractory lining is reduced and less slag
is typically generated (Taft (1995) and Jain (1986)).
Cokeless cupolas can be used in conjunction with electric furnaces to maximise
overall process efficiency. Cupolas are recognised as being highly efficient at
melting metal. As the taping temperature is increased, however, the efficiency
of the cupola decreases significantly (Brown, 1994). Electric furnaces are the
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
most efficient at superheating the metal. In duplexing systems, cupolas are
used to melt the charge and electric furnaces are then used to superheat and
to hold the molten metal (Taft, 1995).
The development of cokeless furnaces may reduce the migration to electric
furnaces. Another area of research that may improve the performance of these
systems is the development of automated controls. At present, cupola furnaces
are operated manually. Operator experience is relied upon to achieve the
desired melt rate, metal composition and metal temperature. The efficiency of
the cupola furnace can be improved significantly by using appropriate sensors
and controls. However, the high temperature environment of the cupola, as well
as the complex interactions between inputs, outputs and control variables
currently makes developing intelligent control technology difficult (Larsen et al.,
1997).
A cupola furnace is usually equipped with an emission control system. The two
most common types of emission collection are the high-energy wet scrubber
and the dry baghouse. Use of the baghouse requires prior cooling of the flue
gases, usually by heat exchange with ambient air (Environment Canada, 1997).
3.2 Electric Induction Furnaces
Induction furnaces have become the most widely used furnaces for melting iron
and, increasingly, for non-ferrous alloys. These furnaces have excellent
metallurgical control and are relatively pollution free (in comparison to cupola
furnaces) (Environment Canada, 1997). The two most common induction
furnaces are the coreless furnace and the channel furnace.
The basic principle of induction furnaces is that a high voltage in the primary
coil induces a low-voltage, high current across the metal charge which acts as
a secondary coil. Because of electrical resistance in the metal this electrical
energy is converted into heat which melts the charge (Metal Asia, 1999c). Once
the metal is in its molten state the magnetic field produces a stirring motion.
The power and frequency applied determine the stirring rate. This is controlled
to ensure complete melting of the charge and adequate mixing of alloy and
fluxing materials, and to minimise temperature gradients in the charge.
Excessive stirring, on the other hand, can increase lining damage, increase
oxidation of the alloys, generate excess slag and increase inclusions and gas
pick-up (Metal Asia, 1998a).
In a coreless furnace (see Figure 5), the refractory-lined crucible is completely
surrounded by a water-cooled copper coil. This prevents the primary coil from
overheating. In channel furnaces, the coil surrounds an inductor. Induction
furnaces are available in capacities from a few kilograms to 75 tonnes.
Coreless induction furnaces are more typically in the range of 5 tonnes to 10
tonnes. Some large channel units have a capacity of over 200 tonnes. Channel
induction furnaces are also commonly used as holding furnaces (Environment
Canada, 1997).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Figure 5: An Electric Induction Furnace (Coreless)
Spout Metal charge
Cooling coil
Induction coil
Refractory
lining
Source: Metal Asia (1998a)
Induction furnaces are very efficient and are made in many sizes. They are
able to melt a wide range of metals but little refining of the metal is possible.
Induction furnaces require much cleaner scrap than cupola furnaces and
somewhat cleaner scrap than electric arc furnaces (USEPA, 1998). The capital
costs are higher than those of electric arc furnaces but the operating costs are
lower due to reduced refractory wear (Jain, 1986). Other advantages of
induction furnaces are that they are relatively simple, very small quantities of
any metal composition can be melted and the melting time is relatively short 鈥?
around 1 hour 鈥? allowing metal to be delivered at small, regular intervals (Jain,
1986).
Approximately 60% of the energy supplied to the furnace is transferred to the
charge. Around 30% of the energy is lost to the cooling water, an additional 7%
lost from radiation and convection losses, and the remainder is lost in the
furnace鈥檚 electrical system (UNEP, 1997).
Energy consumption can be as low as 550 kW.h/tonne but these figures are
achieved only with high utilisation factors and for higher-frequency furnaces
(Taft, 1995). Figures of around 650鈥?750 kW.h/tonne are more typical (Jain,
1986). In comparing the overall efficiency of these systems with that of fuel-
based furnaces, it should be remembered that the electricity has to be
generated and even modern power stations do not reach a 40% efficiency,
which means the overall fuel consumption is well over 2000 kW.h/ tonne
(Powell, 1992)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
3.3 Electric Arc Furnaces
Electric arc furnaces are used for melting high-melting-point alloys such as
steels. The furnace consists of a saucer-shaped hearth of refractory material
for collecting the molten metal, with refractory material lining the sides and top
of the furnace. The roof can normally swing away to facilitate charging of the
furnace. Two or three carbon electrodes penetrate the furnace from the roof or
the sides. Doors in the side of the furnace allow removal of alloys, removal of
slag and oxygen lancing.
The scrap metal charge is placed on the hearth and melted by the heat from an
electric arc formed between the electrodes. In a direct-arc furnace, the electric
arc comes into contact with the metal; in an indirect-arc furnace the electric arc
does not actually touch the metal . Molten metal is typically drawn off through a
spout by tipping the furnace.
Figure 6: A Direct Arc Furnace
Electricity supply
Carbon electrodes
Spout
Door
Metal
Rammed
hearth
Source: Metal Asia (1999c)
As the refractories deteriorate, slag is generated. Fluxes such as calcium
fluoride may be added to make the slag more fluid and easier to remove from
the melt. Refractory life can also be extended by forming protective slag layers
in the furnace, by intentional addition of silica and lime. The slag protects the
molten metal from the air and extracts certain impurities (Environment Canada,
1997).
Electric arc furnaces are more tolerant of dirty scrap that induction furnaces
and can be used to refine metals, allowing steel to be refined from an iron
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
charge (USEPA, 1998). Direct arc furnaces have a very high thermal efficiency
鈥? around 70% 鈥? and can function at as little as 450鈥?550 kW.h/tonne of metal
melted. Indirect electric arc furnaces typically achieve closer to 700鈥?1000
kW.h/tonne of steel (Jain, 1986).
3.4 Rotating Furnaces
Rotating furnaces consist of a refractory-lined cylinder that rotates slowly
around a horizontal axis. The charge is heated directly from an open flame,
typically fed by either gas or oil. Exhaust gases are extracted from the opposite
end of the chamber. Rotating the furnace helps to mix the charge and utilises
heat from the whole refractory surface.
Immediately after melting, the melt is covered with a layer of salt. This reduces
slag formation by protecting the melt from oxidisation. Rotating furnaces are
relatively inefficient, at around 990鈥?1080 kW.h/tonne of metal melted, but the
lower cost of fuel offsets this disadvantage to some extent (UNEP, 1997).
Figure 7: A Rotating Furnace
Refractory lined drum
Extraction
filter
Flame
Metal
Rotating
armature
Source: UNEP (1997)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
3.5 Crucible Furnaces
Crucible furnaces are among the oldest and simplest furnaces used in the
foundry industry. They are primarily used to melt smaller amounts of non-
ferrous metals but can also be used for ferrous metals (Metal Asia, 1999c).
They are mostly used by smaller foundries or for specialty alloy lines. The
crucible or refractory container is heated in a furnace, typically fired with
natural gas or liquid propane, although coke, oil or electricity have been used
(USEPA, 1998). There are three common crucible furnaces: bale-out furnaces,
where molten metal is ladled from the crucible; tilting furnaces, where the metal
is poured directly from the furnace; and lift-out furnaces, where the crucible can
be removed from the furnace and used as a ladle (Metal Asia, 1999c).
Figure 8: A Crucible Furnace
Spout
Crucible
Tilting
mechanism
Metal
Refractory
lining
Burner
Source: UNEP (1997)
3.6 Environmental Issues
Cupola, reverberatory and electric arc furnaces may emit particulate matter,
carbon monoxide, hydrocarbons, sulfur dioxide, nitrogen oxides, small
quantities of chloride and fluoride compounds, and metallic fumes from the
condensation of volatilised metal and metal oxides. Induction furnaces and
crucible furnaces emit relatively small amounts of particulate matter,
hydrocarbons and carbon monoxide (USEPA (1998) and Environment Canada
(1997)).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
As shown in Table 3, cupola furnaces generate the largest quantity of
emissions per tonne of charge. This is largely due the fact that the charge
material typically includes greater levels of contamination, but is also due to the
use of coke. Cokeless cupola furnaces achieve significantly lower emission
rates. Emissions from electric melting furnaces are relatively low. They typically
include gases and dust, which originate from contamination in the charge such
as oil, dirt and rust. Most emissions occur during a short period after charging.
The emissions also include fine metal and oxide particles. Generally, higher-
frequency induction furnaces will generate less of this material because lower
stirring rates result in less contact between the metal and air (UNEP, 1997).
Electric induction furnaces achieve the lowest emissions, particularly for steel
foundries where emissions can be virtually eliminated.
Slag is also generated during metal melting operations. Hazardous slag can be
generated if the charge materials contain enough toxic metals, such as lead
and chromium, or if calcium carbide is used in the metal to remove sulfur
compounds (USEPA, 1998).
Table 3: Emission Factors for Uncontrolled Furnaces
Process Grey iron foundries Steel foundries
(kg/tonne) (kg/tonne)
Cupola 8.5
Electric arc 5 6.5
Electric induction 0.75 0.05
Reverberatory 1
Note: Emissions are expressed as weight of pollutant per weight of metal
melted.
Source: Environment Canada (1997)
These emission factors, for fugitive particulate matter from grey iron foundries
using an electric arc furnace, are broken down by process in Table 4.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Table 4: Emission Factors for Fugitive Particulates
from Grey Iron Foundries (Electric Arc
Furnace)
Process Emissions Emitted to work Emitted to
environment atmosphere
(kg/tonne)
(kg/tonne) (kg/tonne)
Scrap and charge 0.3 0.25 0.1
handling, heating
Magnesium treatment 2.5 2.5 0.5
Sand handling and 20 13 1.5
preparation
Core making, baking 0.6 0.6 0.6
Pouring 2.5 2.5 1
Cooling 5 4.5 0.5
Shakeout 16 6.5 0.5
Cleaning, finishing 8.5 0.15 0.05
Note: Emissions are expressed as weight of pollutant per weight of metal
melted.
Source: Environment Canada (1997)
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Part 6: Cleaner Production Guideline
1. Introduction to Cleaner Production
1.1 What is Cleaner Production?
Cleaner Production aims to prevent pollution, reduce the use of energy, water
and material resources and minimise waste, profitably and without reducing
production capacity. It involves rethinking conventional methods to achieve
鈥榮marter鈥? products, product components, and production processes.
The United Nations Environment Program (UNEP) defines Cleaner Production
as 鈥榯he continuous application of an integrated preventive environmental
strategy applied to processes, products, and services to increase eco-efficiency
and reduce risks to humans and the environment鈥?. It includes:
Production processes: ... conserving raw materials and energy, eliminating
toxic raw materials, and reducing the quantity and toxicity of all emissions and
wastes.
Products: ... reducing negative impacts along the life cycle of a product, from
raw materials extraction to its ultimate disposal.
Services: ...incorporating environmental concerns into designing and
delivering services.
Cleaner Production requires changing attitudes, responsible environmental
management and evaluating technology options.
1.2 How is Cleaner Production different?
Foundries use a lot of different materials and produce wastes that represent a
cost to the company and can have an impact on the environment if they are not
managed effectively. The wider community and governments may also face
significant costs for treating and disposing of wastes and for repairing damage
to the environment. These costs can be high and trends show that they are
rising as pressure on the environment increases.
Traditional environmental protection focuses on what to do with wastes and
emissions after they have been created. Treatment and disposal of waste
generally only address the symptoms of an inefficient process. Waste is often
an indicator that you are losing money unnecessarily.
The goal of Cleaner Production is to avoid generating pollution in the first place
- which frequently cuts costs, reduces risks and identifies new opportunities.
Cleaner Production aims to reduce waste and inefficiency at source and can
help develop the most efficient way to operate processes, produce products
and to provide services.
It can save your company money!
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Improving environmental performance by reducing wastes and emissions is a
major focus of Cleaner Production. Improved health and safety and also be an
outcome of the process. Other benefits include new markets and business
opportunities.
Cleaner Production provides an integrated approach that highlights both
economic and environmental improvement. By using this approach, improving
environmental performance and reducing the risk of causing environmental
harm or nuisance becomes a natural outcome of running an efficient process.
1.3 The Cleaner Production Hierarchy
The Cleaner Production Hierarchy is a good tool to help think about Cleaner
Production options in your operation and to focus on eliminating or reducing
waste at source. In adopting a Cleaner Production philosophy, try to consider
how wastes were created rather than how they can be treated. Typically,
strategies higher up the hierarchy are more cost effective.
Figure 1: The Cleaner Production Hierarchy
Focus Strategy
Eliminate Pollution
Prevention
Reduce
Waste
Reuse
Management
Recycle
Treat & Control &
Dispose Disposal
All media Impact of
Air, Water, Soil Products
Personnel Management
Raw Materials Use Energy Work Procedures
1.3.1 Eliminate
Eliminating the need to use materials (particularly harmful products such as
cleaning agents) can greatly reduce operating costs and reduce the potential
harm to the environment, for example, by substituting hazardous materials with
less harmful alternatives.
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1.3.2 Reduce
The next step is to minimise the use of all materials in the process. This can
include reducing errors in batch preparation, optimising cleaning operations to
reduce the volume of water used and turning off equipment that is not in use.
1.3.3 Reuse
There are many opportunities to reuse 鈥榳aste products鈥? in the foundry industry.
This will reduce the demand for raw materials and the cost of treatment and
disposal. It may be possible to reuse sand internally or to reclaim waste heat
from one process for use in another.
1.3.4 Recycle
Are the wastes identified by your assessment really 鈥榳astes鈥?? Can some of
these be reclaimed through simple treatment processes that enables them to
be recycled on-site? Other by-products that cannot be used on site may be
recycled off-site. In these cases there may be the potential to sell recyclable
items and also save by the avoiding disposal costs.
1.3.5 Treat and Dispose
This option should only be considered after the other options have been
exhausted. Generally these options are typically a cost to industry. However it
may be essential to consider this as a part of your overall Cleaner Production
strategy. The costs of treatment can be minimised by focusing on the previous
options.
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2. Implementing a Cleaner Production Project
A Cleaner Production assessment is
Figure 2: Implementation a systematic approach to identify
Guide areas throughout the process where
resource use, hazardous materials
and waste generation can be
Phase I: Planning and Organisation
reduced. While there are several
鈥? Management Commitment
approaches to undertaking CP
鈥? Set up a Project Team
assessments all of them have a
鈥? Develop Environmental Policy
similar underlying purpose - to
鈥? Plan the Cleaner Production Assessment encourage a formal / systematic
examination of the company鈥檚
operation, to capture all ideas in the
system so they can be evaluated and
Phase II: Pre-Assessment (qualitative review) implemented as appropriate, and to
鈥? Company Description help maintain focus and progress
鈥? towards the goals of the project.
Process Flow Chart
鈥? Walk-Through / Site Inspection
Informal programs tend to start well
鈥? Plan Assessment Phase
but can lose drive over time as day-
to-day pressures shift focus
elsewhere. Non-systematic projects
run the risk of focusing too much
Phase III: Assessment (quantitative review)
effort on areas with relatively modest
鈥? Collection of Data
potential gains.
鈥? Material Balance
The level of detail necessary varies
鈥? Identify Cleaner Production Options
between companies and should be
鈥? List Options
guided by the potential benefits that
can be gained from the program -
including cost savings,
environmental and other benefits.
Phase IV: Evaluation and Feasibility Study
鈥? The project scope also varies
Preliminary Evaluation
鈥? between companies. The pre-
Technical Evaluation
assessment phase (Phase II) should
鈥? Economic Evaluation
help to broadly define the scope of
鈥? Non-Economic Evaluation
the project and the assessment
phase (Phase III) should accurately
measure resource use and waste
throughout the process and identify
Phase V: Implementation and Continuation
process areas that are major
鈥? Prepare an Action Plan
contributors to the overall problem.
鈥? Implementation of Cleaner Production Options
This will help set priorities and
鈥? Monitor Performance
ensure that your company鈥檚
鈥? Sustain Cleaner Production Activities
improvement actions will have the
biggest impact for the effort
expended.
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3. Planning and Organisation
3.1 Getting Started
Is your company ready to implement a successful Cleaner Production program?
There are a number of factors that appear to contribute most significantly to the
success of company based programs, for example, getting top management
support.
Think about the company culture and systems that help or inhibit Cleaner
Production uptake.
3.1.1 Support
Companies are more likely to succeed when:
鈥? management support the program for Cleaner Production / waste
minimisation.
鈥? top management drive change by communicating the benefits of Cleaner
Production to all staff.
鈥? sufficient time and resources have been allocated to achieve the Cleaner
Production objectives.
鈥? the company has a challenging Environmental Policy that encourages
source reduction and continuous improvement.
3.1.2 Acceptance
Companies are more likely to succeed when:
鈥? staff are aware of Cleaner Production.
鈥? staff understand the economic and environmental importance of reducing
waste.
鈥? staff understand and support their role in achieving the objectives of the
program.
3.1.3 Planning
Companies are more likely to succeed when:
鈥? the Cleaner Production project is formalised and well planned.
鈥? the project has an established framework, with a team leader, team members
and clear roles and responsibilities.
鈥? when the budget, timeframe, goals and success criteria are clearly defined
and measurable.
鈥? when progress is regularly reviewed and drive is maintained (by top
management, the CP team leaders and everyone in the company).
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3.1.4 Knowledge
Companies are more likely to succeed when:
鈥? the project is based on good information. This can be gained from Cleaner
Production / environmental or efficiency audits for energy, water, trade
waste, materials etc..
鈥? the company can set reasonable priorities based on the full value and impact
of waste generated by the company.
鈥? the procedures for identifying, evaluating and implementing Cleaner
Production options are well known, supported and widely practised
throughout the organisation.
鈥? staff have sufficient training in correct waste minimisation procedures and
know what to do with each type of waste (e.g. laminated signs posted around
the site).
鈥? staff know what to do with waste in the case of an accident / emergency.
鈥? the company has an effective and timely materials accounting system in
place - integrating purchasing, handling, inventory, process control and
sales systems - to accurately track resource use, waste and produce
variance reports (i.e. that compare actual and standard resource use and
waste).
鈥? orientation programs for new employees include Cleaner Production.
3.1.5 Skills
Companies are more likely to succeed when key staff have the necessary skills
to:
鈥? implement appropriate waste measuring and monitoring systems.
鈥? undertake Cleaner Production assessments / audits.
鈥? identify resources and product losses (emissions, wastewater and solid
waste).
鈥? identify Cleaner Production improvement opportunities.
鈥? evaluate options (economic and non-economic analysis).
鈥? implement viable options.
3.1.6 Improvement and Feedback
Companies are more likely to succeed when:
鈥? progress is reviewed on a regular basis (e.g. annually) at a corporate level.
鈥? staff are fully involved in the suggestion and improvement process.
鈥? performance reviews include Cleaner Production goals.
鈥? two-way communication exists between employees and management.
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鈥? feedback about achievements and improvements is regularly reported (e.g.
KPI progress reports and wall charts).
鈥? feedback is provided for all suggestions (even those that cannot be
implemented).
鈥? the cost of resource use (e.g. energy, water), waste generation, treatment
and disposal and other overheads is allocated and charged to individual
process units in accordance to the contribution of each.
鈥? the goals of Cleaner Production are integrated into the overall business
objectives of the organisation.
These success factors have been derived from a large number of Cleaner
Production projects. Your project may, of course, succeed without some of
these factors. They do not guarantee success, but they are a good guide based
on previous experience.
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4. Pre-Assessment
The pre-assessment is designed to give an overview of the organisation. This
involves collecting or developing some basic process information that allows
your company to set the broad scope of the Cleaner Production project. This
information will also form the basis of the assessment and evaluation phases.
Process Flow Diagrams
Figure 3: Simplified Foundry Flowchart
One of the best methods
Metal
for collecting this Slag
Alloys
information is to develop Heat
Pour
Fluxes
process flowcharts for Emissions
Sand
each process in the Refractories
operation. These Energy
Cooling
flowcharts should identify
(at least) the major inputs
and outputs (including Shakeout Sand
by-product and wastes)
in each process step. A
simple example is shown Castings
in Figure 3.
Runners
Grinding
The Walk Through Risers
consumables
Assessment Swarf
Fettling
Energy
Grindings
One method of Spent shot
undertaking a simple
Cleaning
pre-assessment is to
undertake a Walk
Through Assessment.
Inspection Scrap
This is a simple method
that takes the CP team
through each step of the
Finishing
process and encourages
them to identify waste
problems and to identify
Finished casting
opportunities for
improvement.
The assessment can be done away from the process area by using process
flow diagrams but it is often better to physically walk through the area as this
will provide lots of cues (e.g. waste on the floor, sounds of air leaks etc.) and
allow you to talk to process staff.
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4.1 Steps
1. Form a team for the Walk Though Assessment. Include people who
understand the process and some from outside the process who might
question things that those close to the process take for granted.
2. Schedule an appropriate time for the assessment - you may need one to
two hours depending on the scale of the operation.
3. Start by reviewing the process (use a process flow diagram) to ensure
everyone on the team understands the key process steps.
4. Walk through the process considering all aspects of waste, resource use
and efficiency.
5. Record all the waste problems and improvement ideas you identify.
6. Prioritise the problems and opportunities. Use this information to plan the
assessment phase.
The purpose of this process is to identify the range of issues and opportunities
facing the company and begin to assess the priority areas that are likely to
have a significant positive impact on the company鈥檚 performance. This
information should be used to plan the Assessment phase and set broad
priorities. Don鈥檛 eliminate areas from the assessment at this stage. More
detailed and quantitative analysis in the assessment phase (e.g. mass
balances, monitoring and measuring programs) will provide a more systematic
approach to targeting your improvement actions.
The following checklist may provide a useful approach for thinking about the
key issues and recording problems and opportunities that are identified in the
process. This is a very broad checklist designed to flag major issues in the
short amount of time typically available for the assessment. More exhaustive
checklists are provided in the Cleaner Production Checklist series. You may
prefer to use these (and any other ideas you have) to develop a checklist that
is more relevant to your operation.
Table 1: Simple Walk-through Assessment Checklist
Questions Notes
(Problems Identified)
Inventory Issues
Are products stored and handled to
minimise breakages, spoilage etc.?
Do we maintain an effective inventory
system(e.g. first in - first out, Just-in-
Time)?
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Questions Notes
(Problems Identified)
Do errors in the materials make-up
area and procedures create waste?
Does the type and quality of our
inputs lead to waste?
Process Issues
Are there any drips or leaks in the
area?
Are there any spills on the ground?
Can they be avoided or reused?
Where do they go?
Are there any areas where spills or
process foul-ups can occur?
Are there any bottlenecks where
production is held up?
Is the machinery and equipment
operating at its designed capacity /
efficiency?
Is energy being wasted?
How does the layout of the plant
impact on the efficiency of the
operation?
Is there any equipment available that
could increase efficiency?
Housekeeping Issues
Are there any obvious signs of poor
housekeeping practices?
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Questions Notes
(Problems Identified)
Are there any methods available to
improve cleaning practices?
Does the layout of the plant make
housekeeping, cleaning and
maintenance difficult?
Staff Issues
Do the operating procedures lead to
the generation of waste? Can they
be changed?
Do staff have any other ideas for how
waste can be reduced?
Are procedures being followed? If
not, why not? What procedures do
the staff have difficulty with? Do they
have any suggestions for how they
might be improved?
Have staff had the opportunity to
suggest and make changes that
improve efficiency?
Waste Issues
How are wastes removed from the
process area?
Are wastes segregated?
Are there any opportunities for reuse
or recycling of wastes?
Is waste treated on site? Could any
wastes be recycled after treatment?
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Questions Notes
(Problems Identified)
How is waste removed from the site?
Marketing Issues
What are the product specifications
and customer requirements? How do
these impact on the creation of
waste? Can they be changed?
Are there any potential marketing
benefits to be gained from our
Cleaner Production program?
Broad Issues
Can we suggest any changes to the
company鈥檚 overall policies and
systems that would help implement
Cleaner Production in this area?
Are there any long term changes to
equipment, facilities, markets that
should be considered?
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5. The Assessment
The assessment phase involves the collection of data that enables you to
evaluate the environmental performance, production efficiency and wastes
generated by the company. Information should be collected at the company
level to allow overall performance to be measured, for targets to be set and for
progress to be monitored. Process information is also necessary to identify the
sources of problems and opportunities for improvement.
5.1.1 Collecting Information
Information can be sourced from a large number of areas. The main types of
information and possible sources include:
鈥? Production
External Requirements and scheduling
records.
鈥? Relevant environmental laws and
鈥? Process
regulations and likely trends. and equipment
specifications.
鈥? Environmental Management
鈥? Quality assurance procedures
Systems and Standards.
and records.
鈥? Industry codes of practice.
鈥? Information from suppliers.
Cleaner Production Information
鈥? Flow meters and process control
鈥? Manuals, checklists, guidelines.
data.
鈥? Case studies, demonstration
Cost Data
projects.
鈥? Council rates notices, trade
鈥? Consultants, government
waste statements and waste
departments, universities.
management contracts.
Process information
鈥? Waste handling, treatment, and
鈥? Process flow diagrams.
disposal costs.
鈥? Design and actual layouts.
鈥? Water and sewage costs,
鈥? Operating manuals and process including surcharges.
descriptions.
鈥? Costs for non-hazardous waste
鈥? Equipment layout and logistics. disposal (e.g. scrap metal,
鈥? Equipment specifications and cardboard).
鈥? Product, energy and raw material
data sheets.
Operational Information costs.
鈥? Operating
鈥? Product composition and batch and maintenance
costs.
sheets.
鈥? Purchasing,
鈥? Material Safety Data Sheets. invoice and
inventory records.
鈥? Product and raw material
鈥? Wages.
inventory records.
鈥? Treatment cost records.
鈥? Operator data logs.
鈥? Licensing Costs.
鈥? Operating procedures.
鈥? Production schedules.
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Where information is not available it may be necessary or desirable to
undertake specific monitoring programs to collect data. These may include
energy / resource efficiency or waste (solid waste, wastewater etc.)
assessments.
5.1.2 Materials Balance
Developing a materials balance is a systematic approach to tracking materials
through the operation. A thorough analyses would include solids, liquids,
gasses and energy flows. The basic principle is that 鈥渨hat goes in - must come
out鈥?. This enables you to identify losses in the process and identify where they
are coming from. It also helps determine the significance of each area of loss
and target the most important losses. A simple materials balance is shown in
Figure 4.
Figure 4: Partial Materials Balance for a Typical
Foundry
Metal: 1.7 tonne
Iron Final Product: 1 tonne
Recycled Metal: 800kg
Foundry
Alloys: 300kg
Slag: 250kg
Flux: 200kg (1 tonne final Metal loss: 150kg
castings)
Electricity: 1300 kW.h Waste energy: 650kW.h
Note: data is indicative only.
The materials balance can be developed broadly for the entire operation. At the
process level, the analysis will be more meaningful and allow better decisions
to be made. The level of detail should be dictated by the importance of the
decision. If company wide material balance indicates significant opportunities
for improvement then a more detailed analysis may be justified.
In order to develop priorities, this resource balance should include the volume
of the material, the nature of the material (e.g. potential risks) and the full
economic value of the material to the company. This will help to target the
areas that have the most significant environmental risk and represent the most
significant economic cost to the company.
If it proves to be very difficult to undertake a materials balance it may point to
opportunities to improve process control and materials accounting practices.
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5.1.3 Developing Costing Information
Calculating the actual costs of production is crucial in setting priorities for
improvement and persuading yourself and others of the benefit of Cleaner
Production. For most companies, the most accurate data available is typically
site-wide data such as purchasing records, total production / sales, inventory
stock takes etc.. Therefore, the easiest approach to allocating costs at the unit
operation level is typically a breakdown method. The steps for this method are:
Step One - estimating overall cost of each waste stream to the company.
This calculation will include the cost of:
鈥? materials purchasing and handling.
鈥? production.
鈥? cleaning and maintenance.
鈥? monitoring, treatment, disposal.
鈥? compliance.
There may be a wide range of other on-costs and overheads that need to be
considered.
The site wide materials balance should provide data for each material on the
quantity purchased, the amount leaving as valuable products and the amount
that ends up as waste. This ratio of inputs to waste outputs will help calculate
the proportion of materials costs that should be assigned to waste.
For example:
Table 2: Calculating the full cost of resources
Input Monthly Monthly Proportion Monthly Cost Monthly Cost
Input Waste Waste of Inputs of Wastes
Metal 600 12 tonnes 2% $96,000 $1,920
tonnes
Note: Data provided is for example only.
The other costs can be assigned to individual waste streams based on their
contribution to various costs. This could be calculated by volume (e.g. waste
accounts for 2% of total material intake, therefore, the full cost should include
2% of production, cleaning and maintenance costs). There may be other
methods of allocating costs (e.g. risk based) that may be appropriate.
Step Two - estimate the cost per unit of waste
Dividing the total cost of each waste stream by the total quantity generated in
the period will provide an estimate of the unit cost of the waste. In the example
above, the unit cost for waste metal is $4000 / tonne.
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Step Three - assign waste costs of unit processes.
Undertaking a detailed mass balance will provide data on the volume of
materials wasted in each unit process. Unit costs of waste can then be used to
assign total costs of waste to each unit process. This will help identify which
processes contribute most significantly to the costs of waste. This approach
can be used to calculate total cost for unit operation or show the contribution of
all unit processes for an individual waste stream.
For example:
Table 4: Waste Stream -
Table 3: Unit - Melting
Metal
Input Quantity Cost Unit Process Quantity Cost
(%)
Metal 600t $96,000 Metal loss on .6 $576
ignition
Alloys 20t $6,000 OR Spills and .8 $768
pigged metal
Fluxes 5t $1,600 Scrap .6 $576
/grinding loss
Total $103,600 Total 2 $1,920
Note: Data provided is for example only. Note: Data provided is for example only.
5.1.4 Identifying Causes of Waste
Once you have measured the quantity and cost of waste, the next step is to
identify the causes. Some causes of waste may be unavoidable. For others the
cost of fixing the problem may be greater than the benefits that will be gained.
However, experience shows that many causes are avoidable.
Identifying causes may require brainstorming, further investigation or expert
advice. Typical causes include:
鈥? storage and product conveyance (e.g. leaking tanks, pipes, spillages);
鈥? poor process control or lack of process optimisation;
鈥? faulty or old equipment;
鈥? inappropriate or poorly followed operating procedures;
鈥? poor maintenance routines; and
鈥? poor housekeeping practices.
Identifying the real cause of waste is necessary for the next step - generating
appropriate CP options.
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5.1.5 Generating CP Options
There are a wide range of methods that your company can adopt to generate
ideas for Cleaner Production improvements. Whatever methods you choose, it
is important to ensure that:
鈥? participation in the process is encouraged.
鈥? that the ideas are documented and not lost.
鈥? that all ideas are given an appropriate level of consideration.
鈥? timely feedback is given for each idea (even unsuccessful ones).
鈥? good ideas are rewarded.
Your idea generation method may be as simple as providing suggestion boxes
or asking staff for their opinion.
You may also develop a more formal improvement suggestion process. For
example, Quality Assurance and Environmental Management systems typically
include the use of improvement suggestion forms which can be used for this
purpose.
Cleaner Production workshops and brainstorming sessions are also used to
generate ideas, often as part of training programs. There are many
brainstorming techniques that you can use. The idea of these techniques is to
encourage staff to look at processes from a Cleaner Production perspective.
Being closely involved in a process can make it difficult to see problems and
opportunities for improvement. Therefore is it necessary to use techniques that
encourage you to see the process with 鈥榓 new set of eyes鈥?.
One good method is to use Cleaner Production checklists. For example, the
walk-through assessment you undertook as part of the pre-assessment should
have uncovered a number of options that were immediately apparent.
Discussing each of the problem areas identified in the walk-through should
help develop many more. The Cleaner Production ideas section (see Part 2)
provides a lot of ideas which are summarised in the self assessment guide (see
Part 4).
You may choose to use some brainstorming exercises that you can use to help
think laterally about possible solutions. The following questions may help.
1. Think about each of the key words from the hierarchy in turn - elimination,
minimisation, reuse, recycling, treatment, disposal. What options does this
generate?
2. Think about the possible Cleaner Production strategies - housekeeping,
input change, simple process change, major process / technology change,
product or market change. What options does this generate?
3. Try to distinguish the causes from the symptoms. Waste on the floor is a
symptom of a bad procedure or faulty equipment. What is the cause of the
problem and how can these be fixed?
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4. What assumptions are you making? Just because this is always how it has
been done doesn鈥檛 mean it is the only way.
5. What are the rules, procedures, and guidelines that affect the area? Do
these cause unnecessary waste?
6. Where does the waste go and what problems does this cause? Is there
anything else that could be done to this waste?
7. What can you do today? The best solution may take a long time to
implement. This doesn鈥檛 mean something couldn鈥檛 be done in the meantime.
What is the simplest solution to the problem that you could implement
today?
8. No matter what you do someone will be there to say 鈥榠t can鈥檛 be done鈥?. What
negative reactions can you expect? What excuses could be made to stop
progress? What are the impediments to minimising waste? How can you
overcome these?
6. Evaluating Cleaner Production Options
Many improvement options are relatively simple so costs and benefits of
implementing them are fairly clear. For more complex options it may be
necessary to undertake an evaluation to ensure it is beneficial to the company
in the long term. Also, you may have developed a number of potential projects
and need to establish which ones to implement within budget limitations.
Simple options with clear benefits should be implemented immediately.
For more complex decisions, option evaluation should be undertaken to the
appropriate level and should include both economic and non-economic criteria.
The economic analysis will provide an idea of the cost involved in implementing
the options, on-going costs associated with the change and the potential
benefits associated with reduced costs, increased sales and profits. The non-
economic analysis will consider how the change will impact on the
organisation.
The detail of the analysis should match the importance of the decision. Projects
that are costly and involve significant changes will have to go through a more
detailed evaluation process as part of the company鈥檚 overall planning process.
Simple projects with obvious benefits may get immediate approval.
6.1 Economic Analysis
In order to complete the economic analysis, you will need to estimate all major
costs and benefits associated with the project. The table below will show you
most of the categories you should consider.
1. Determine the likely cost of equipment and installation and any other up-
front costs associated with change - e.g. housekeeping changes are
typically cheap.
2. Estimate the likely on-going costs such as running costs, maintenance,
materials, labour, etc.
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3. Is the change likely to lead to increased sales of current or new products -
what range may be likely?
4. What level of savings may be possible from the change in terms of
materials, water, energy, treatment, disposal etc?
5. Are there any other costs or benefits associated with the change? Can they
be quantified?
6. Estimate the total costs and the total benefits for the option.
7. Calculate the net annual benefit by subtracting the total costs from the total
benefits.
8. Calculate the payback period using the following formula:
Payback = (capital costs / (annual benefits - annual costs)) * 12
This will tell you the approximate number of months it will take to recover
the capital costs associated with the change.
Table 5: Economic Analysis
CP Option Item Value
Equipment
Capital Costs
Installation
Total Capital Costs
Running Costs
Annual Costs
Maintenance
Materials
Total Annual Costs
Increased Sales
Annual Benefits
Sale of By-products
Annual Savings:
Materials
Water
Energy
Treatment / Disposal
Total Annual
Benefits
Net Annual
Benefits
Payback Period
Value Range: 1: < $500; 2: $500 - $5000; 3: $5000 - $20000; 4: $20000 -
$100000; 5: > $100,000
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For example: Installing drip guards may cost $500 and involve no on-going
costs. Cost savings amount to $50 per week or $2600 a year.
Capital costs = $500
Annual costs = $0
Annual benefits = $2600
Payback = $500 / ($2600 - 0) * 12 = 2.3 Months
Note: If you only require a fairly simple analysis or if accurate estimates of
costs and benefits are not available, use the broad value ranges at the
bottom of the table for each item.
6.2 Non-economic Analysis
Non-economic factors also need to be considered to ensure that the change
will not impact negatively on other functional areas in the operation. For each
option being considered, consider the impact on the change on product quality,
safety, customer expectations, environmental performance, and other
management systems in the company.
Table 6: Non-Economic Analysis
Non-economic Factor Comment
How will the change affect product
quality (positive/negative)? Are any
trade-offs acceptable?
How will the change affect health and
safety (positive/negative)?
What are your customers
expectations? Would they care about
the change? What changes would they
accept or even find desirable?
What impact will the change have on
the environmental performance of the
company (i.e. reduce the toxicity or
impact of wastes, reduce environmental
liability etc.)?
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
What are the requirements of people in
different departments (i.e. purchasing,
cleaning, production, maintenance)?
What is the best compromise solution?
How easy will it be to implement the
change? How much time, and
expertise will be needed? Are these
resources readily available?
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
7. Implementation and Review
7.1.1 Project Implementation
While the actual implementation plan for successful options will have different
features depending on the management strategy of the company carrying out
the CP program some desirable features are to:
鈥? Develop the project budget.
鈥? Develop implementation time tables for all recommendations and allocate
tasks to staff members.
鈥? Establish milestones for tasks and monitor their progress.
鈥? Regularly report on progress to CEO.
鈥? Review the results.
7.1.2 Monitoring Performance
Just as measuring waste and resource efficiency is necessary to setting
priorities and developing and implementing action opportunities, monitoring
performance over time is an essential component of your improvement
program.
Many companies use Key Performance Indicators to track changes in
performance. With appropriate monitoring programs, environmental and waste
criteria can be developed. These should include totalised indicators that
monitor the overall environmental impact of the operation (e.g. tonnes of waste
produced per month) and normalised indicators (e.g. resource consumption per
tonne of product, waste generation per unit of production or per unit of input
etc.) that monitor the efficiency of the operation.
Monitoring may also be continuous (e.g flow meters, process control data
loggers) or periodic (e.g waste audits, wastewater monitoring, manual stock
takes). The cost and complexity of the system may also vary from simple
manual systems to sophisticated real time process monitoring systems that
integrate purchasing, inventory, dispensing and production to allow detailed
materials accounting throughout the process. In general, your monitoring
system will add value to the organisation if the value of the information is
greater than the cost of the system.
In the foundry sector, the full costs of waste and resource inefficiency are
typically high and many companies are realizing the benefits of developing
sophisticated process monitoring systems. These systems can be used to
generate variance reports that compare real time resource use and waste data
with established norms. Major differences (in terms of value and volume) can
be highlighted and associated with a specific process and time period. This
enables the supervisor / manager to pinpoint the problem and deal with it
quickly - before the cause is forgotten or further waste of created.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
7.1.3 Continuous Improvement
To achieve continuous improvement the momentum of the Cleaner Production
project must be maintained over time. Some of the factors that will help achieve
this include:
Providing Timely Feedback
Most Cleaner Production solutions are not purely technical in nature. Therefore
sustaining and building on improvements over time requires active staff
participation. This is most likely to occur when staff can identify tangible
personal benefits from their involvement. These may be both financial and non
financial rewards. The desire for recognition, perceived meaningfulness and
pride in work (e.g. that their company is responsibly caring for the environment
etc.) are all sources of motivation.
Providing timely feedback to staff and acknowledging and rewarding success
is, therefore, essential for achieving continuous improvement. This feedback
should include circulating Key Performance Indicators and assessment / audit
results, promoting all successes and giving timely responses to all
improvement suggestions (even unsuccessful ones).
Integrating Cleaner Production
Your Cleaner Production program will be more sustainable if the program is
integrated into the overall company culture. Rather than being treated as a
separate project, Cleaner Production should be integrated with and have equal
status to programs such as quality assurance, health and safely, environmental
management, hazard analysis etc.
Cleaner Production should be built-in to the decision making process of the
organisation. This will mean that projects that require long term commitment
can be evaluated along with other demands for capital in the company and be
included in long term financial plans.
Changing the culture of a company does not happen overnight, but making
Cleaner Production the way people work will contribute to making your
organisation a dynamic learning environment.
Periodic Evaluation and Review
Progress towards Cleaner Production goals should be reviewed at the senior
management level on a periodic basis. Once a year should be appropriate in
most cases. This should include a detailed review of all improvements, results
of monitoring programs and future plans. At the project level, progress should
be reviewed more frequently.
Including Cleaner Production responsibilities and targets in staff job
descriptions and performance appraisal procedures may also be an
appropriate method of periodic review that encourages and rewards on-going
involvement.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Glossary
Many of the terms listed in the glossary are described in greater detail in Part
5: Overview of Foundry Processes.
Alloy A substance having metallic properties and composed of
two or more chemical elements of which at least one is
metal. Usually possesses qualities different from those of
the components.
Baghouse dust Small solid particles created by the breaking up of larger
particles by an process. Typically dusts are created in the
foundry industry from metals, sand, and other refractories.
These materials are often collected in baghouses
(extraction and filtration systems).
Binders Materials, both organic and inorganic, that are added to
the mould materials to achieve sufficient mould hardness.
CAD / CAM Computer-Aided Design / Computer-Aided Manufacture.
Captured foundry Refers to a foundry operation that that is wholly
incorporated into a larger manufacturing operation and
produces castings exclusively for that operation.
Casting The process of pouring molten metal into a cavety to form
a solid metal shape.
Charge The metal and alloy materials that comprise the melt.
Core Part of the mould which forms the internal shapes or parts
of a casting which cannot be shaped by the pattern.
Crucible furnace A furnace fired with coke, oil, gas, or electricity in which
metals are melted in a refractory crucible.
Cupola furnace A traditional furnace that uses coke as the fuel source to
melt the charge.
Dimensional The specified allowable difference in limiting sizes from
accuracy the initial design and the final casting. Precision casting
processes typically achieve higher dimensional accuracy.
Direct-Arc An electric arc furnace in which the metal being melted is
Furnace one of the poles.
Ferrous metal Refers to alloy in which the predominate metal is iron.
This includes iron and steel.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Fettling and The removal of gates, runners, risers and sand from the
cleaning rough casting. Also involves any hand finishing such as
grinding, blasting or polishing.
Flash A thin section of metal formed at the mold, core, or die
joint or parting in a casting due to the cope and drag not
matching completely or where core and coreprint do not
match.
Gating systems Gating systems are designed to allow the metal to flow in
to the mould and to aid appropriate solidification of the
metal. Gating systems typically include the sprue where
the metal is poured, gates which allow the metal to enter
the running system; runners which carry the molten metal
towards the casting cavity; risers which may have several
functions including vents to allow gases to be released,
reservoirs prior to the casting cavity to aid progressive
solidification, and waste cavities to allow metal to rise
from the casting cavity to ensure it is filled and to remove
the first poured metal from the casting cavity, thus
avoiding solidification problems
Green sand A naturally bonded sand mould mixture which includes
silica, bentonite clay, carbonaceous material and water.
Green refers to the fact the material is wet.
Gross weight of The weight of the casting as poured. This includes the
cast actual product plus the metal in the gating system (see
also net weight).
Impurity An element unintentional allowed in a metal or alloy.
Some impurities have little effect on properties; others will
grossly damage the alloy.
Inclusion Nonmetallic materials in a metal matrix. Sources include
reoxidation, refractories, slag, and deoxidization products.
Indirect-Arc An AC (Alternating Current) electric-arc furnace in which
Furnace the metal is not one of the poles.
Induction Furnace A AC melting furnace which utilizes the heat of electrical
induction.
Investment Casting produced in a mold obtained by investing an
casting expendable pattern with a refractory to produce a shell.
The expendable pattern may consist of wax, plastic, or
other material and is removed prior to filling the mold with
liquid metal.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Jobbing foundry Refers to a foundry operation that produces a wide range
of castings, typically in small batches, for various
customers (see also repetitive foundry).
Ladle Metal receptacle frequently lined with refractories used for
transporting and pouring molten metal. Types include
hand bull, crane, bottom-pour, holding, teapot, shank, lip-
pour.
Lining Inside refractory layer of firebrick, clay, sand, or other
material in a furnace or ladle.
Lost Foam Casting process in which a foam pattern is removed from
Process the cavity by the molten metal being poured.
Metal yield Comparison of weight of finished castings to total weight
of metal melted.
Mould The mould forms the cavity into which the metal is poured.
The mould forms the -ve of the final cast shape and also
includes the necessary gating systems. For traditional
two part sand moulds the top of the mould is called the
cope and the bottom is called the drag.
Net weight of cast The weight of the actual casting once all excess metal
from the gating system has been removed (see also
gross weight).
Non-ferrous metal Refers to alloy in which the predominate metal is not iron.
Predominant metals include aluminum, bronze, copper,
gunmetal etc.
Oxidation losses Reduction in amount of metal or alloy through oxidation.
Such losses usually are the largest factor in melting loss.
Oxidizing Furnace atmosphere which gives off oxygen under certain
atmosphere conditions or where there is an excess of oxygen in the
product of combustion, or the products of combustion are
oxidizing to the metal being heated.
Pattern The pattern is a +ve replica of the final casting typically
including the gating systems.
Pigging The practice of pouring excess molten metal into
refractory lined containers for solidification and return to
the furnace.
Quenching Rapid cooling of hardening; normally achieved by
immersion of the object to be hardened in water, oil, or
solutions of salt or organic compounds in water.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Rapid prototyping Equipment used for computerized building of three-
dimensional models and patterns. Enables the data
representation of a CAD solid model to be directly
converted into a plastic model of a casting.
Reducing Furnace atmosphere which absorbs oxygen under
atmosphere suitable conditions or in which there is insufficient air to
completely burn the fuel, or the product of combustion is
reducing to the metal being heated.
Repetitive Refers to a foundry operation that produced continuous
foundry production runs of a set number of castings (see also
jobbing foundry).
Replicast process A ceramic shell process similar to the investment casting
process. Uses a pattern made from expanded polystyrene
and is surrounded by a thin ceramic shell.
Sand Casting Metal castings produced in sand molds.
Sand Processing of used foundry sand grains by thermal,
Reclamation attraction or hydraulic methods so that it may be used in
place of new sand without substantially changing current
foundry sand practice.
Scrap and reject Scrap typically refers to all non-product metal including
runners and risers and reject product. This is also referred
to as foundry returns or " revert ".
Shaw Process A precision casting technique in ceramic molds which do
not require wax or plastic investment.
Shell moulding A process for forming a mold from resin-bonded sand
mixtures brought in contact with pre-heated metal
patterns, resulting in a firm shell with a cavity
corresponding to the outline of the pattern.
Shotblasting Casting cleaning process employing a metal abrasive (grit
or shot) propelled by centrifugal or air force.
TCLP Toxic Characteristic Leaching Procedure. A specific test
to measure the leaching potential of solid waste.
Vacuum Casting A casting in which metal is melted and poured under very
low atmospheric pressure; a form of permanent mold
casting where the mold is inserted into liquid metal,
vacuum is applied, and metal drawn up into the cavity.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
An annotated Guide to Resources Available on
the Internet
This section provides a list of many of the best Cleaner Production resources
available on the web. All the links listed were accurate as at October 1999. If
the sites change in the future, it may be possible to located the new address by
doing a general internet search. In general, Excite and Alta Vista were found to
be the most suitable for locating information on the foundry industry.
The Future of Metal Casting
The Cast Metal Coalition in the United Stated has developed a Metalcasting
Industry Technology Roadmap. This document, accompanied by the report
鈥淏eyond 2000: A vision for the American Metalcasting Industry鈥? provides a
good strategic framework for developing R&D needs for the Australian foundry
industry. These documents are fully down-loadable in PDF format.
http://www.oit.doe.gov/metalcast/roadmap.shtml
Cleaner Production Guides
USEPA Sector Notebook for the Metal Casting Industry
This is an authoritative guide to Pollution Prevention (Cleaner Production) in
the casting industry. This provides valuable background information about the
sector as well as practical improvement opportunities.
http://es.epa.gov/oeca/sector/
Environment Canada Technical Pollution Prevention
Guide for Foundries
This is an excellent guide for practicing foundries offering detailed advice
aimed at cost effective implementation of Cleaner Production programs in the
sector.
http://yvrwww1.pyr.ec.gc.ca/ec/frap/frapdata/frap/pollu.html
Clean Technologies in U.S. Industries: Focus on Metal
Fabrication
This site contains some additional information about clean technology in the
foundry indusrty.
http://www.usaep.org/reports/metal.htm
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Energy Efficiency Best Practice Programme
This site gives details of a the hardcopy publications that can be ordered from
the site. These reports are free of charge to companies within the UK only.
The reports contain valuable information.
http://www.etsu.com/eebpp/
Cleaner Production Case Studies
Cleaner Production Demonstration Project at Auscast
This site provides the full report of the Cleaner Production assessment
undertaking by Dames and Moore Consultants for Auscast in 1994-1997. It
provides detailed of a number of potential projects including sand reclamation,
improved sand quality; trials of new resins and odour control; and improved
recycling of solid waste materials.
http://www.environment.gov.au/epg/environet/eecp/case_studies/cs_aus1.html
Francis W. Birkett & Sons Limited
Article, Foundry casts net over sand waste. This site provides a brief summary
of a sand reclamation project at a foundry.
http://www.waste-management.co.uk/studies/birkett.htm
Decatur Foundry, Inc.
Infrared Drying. This site describes an infrared drying project that helped the
company overcome problems associated with the change from solvent- to
water-based paints.
http://www.aceee.org/p2/p2cases.htm#decatur
KHD Humboldt Wedag.
This case study discusses how an internal reuse of foundry sand reduces sand
waste by 75% and reduces stack emissions at the company.
http://www.unepie.org/icpic/castu/castu152.html
Wolverine Bronze Company
This case study discusses Low Energy Recycling of Foundry Sand.
http://es.epa.gov/techinfo/case/michigan/mich-cs4.html
Progress Casting Group, Inc.
This aluminum foundry replaced TCA with water-based coatings. The case
discusses the Cleaner Production implications.
http://www1.umn.edu/mntap/P2/FOUND/cs93-e1.htm
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Ashley Forge
Common sense approach to hard waste savings. This brief case discusses a
number of opportunities developed at the foundry to reduce some general
waste streams.
http://www.waste-management.co.uk/studies/ashley.htm
The Casting and Development Centre
This site has a number of case studies particularly for CAD/CAM technologies,
casting simulation and other methoding techniques.
http://www.castingsdev.com/
Other Case Study Sites
This site provides a number of brief Cleaner Production case studies for the
foundry industry.
http://www.wmrc.uiuc.edu/packets/primmetals/chapter3.htm
Beneficial Use
Beneficial Use Information Centre
This centre at the University of Wisconsin-Madison USA provides a wealth of
information about potential beneficial use options for the foundry industry. The
site is designed to 1) collect and disseminate published and non-published
information sources, 2) undertake detailed technical reviews of the beneficial
use options, and 3) identify topics in need of research.
http://geoserver.cee.wisc.edu/buic/
CWC Technology Brief, Beneficial Reuse of Spent
Foundry Sand
This brief fact sheet provides some information about a range of potential
beneficial reuse projects.
http://www.cwc.org/briefs/industrial.html
Process Information
TIA Process Information
This site provides a brief description and some technical specifications for
many of the common casting techniques.
http://www.metalbot.com/cast.html
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Wynn Danzur Group
The Wynn Danzur Group presents a summary of many of the major molding
processes.
http://www.wynndanzur.com/toppage1.htm
The Engineering Zone
Other process information is available at this site. As well as a wide range of
casting techniques, this site offers detailed information on rapid prototyping,
rapid tooling and other metal working processes such as forging, machining,
and surface finishing.
http://www.flinthills.com/~ramsdale/EngZone/casting.htm
The Castings Development Centre
The Centre specializes in the Replicast process which, along with conventional
lost foam processes, are explained in some detail at this site.
http://www.castingsdev.com/
Foundry Online
This is a good site for general process information. The site includes
information on the histroy of metal casting, the major processes and new
developments including Rapid Prototyping.
http://www.implog.com/foundry/foundrp.htm
The Hitchener Process
The Hitchener Homepage provides some technical information about the
innovating casting process.
http://www.hitchiner.com/home.html
Casting Source Directory
This directory contains a number of technical articles that discuss the
advantages and disadvantages of a number of casting processes.
http://www.castingsource.com/
Primary Metals
This site contains good process descriptions particularly with reference to sand
reclamation techniques. Several short case studies and diagrams are
included.
http://www.wmrc.uiuc.edu/packets/primmetals/chapter3.htm
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Rapid Prototyping
This site provides a detailed technical report on the emerging technologies of
Rapid Prototyping. Good information on conventional mould casting,
investment casting, casting simulation technology and other foundry processes
is also available here.
http://itri.loyola.edu/rp/toc.htm
Another site that provides useful information on this topic can be found at:
http://www.biba.uni-bremen.de/groups/rp/rp_sites.html
See also:
http://www.biba.uni-bremen.de/groups/rp/rp_page.html
http://www.cs.hut.fi/~ado/rp/rp.html
Casting Simulation Systems
The National Centre for Excellence in Metalworking Technology provides a
number of technical bulletins on advanced forming processes and casting
simulation techniques.
http://www.ncemt.ctc.com/thrustAreas/bulletin/castone.html
A good overview of simulation techniques can be found at:
http://www.castech.fi/ARTICLES/ADI/index.html
See also:
http://mama.minmet.uq.edu.au/cast/service.html
http://www.magmasoft.com
Other Links
Metalcasting Industry Hotlinks
This site has a wide range of links to foundry industry sites on the web.
http://www.oit.doe.gov/metalcast/hotlinks.shtml
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
References
Abdelrahman Dr. M., (1999) Integrated Industrial Process Sensing and Control
System Applied to and Demonstrated on Cupola Furnaces, Prepared by the
Tennessee Technological University for the Sensors and Controls 鈥?99,
Information Exchange Meeting, May.
Allborg University (1998), The Cosworth Process, Available at:
http://www.iprod.auc.dk/procesdb/cosworth/intro/cosworth.htm (Last accessed,
August 1999).
American Council for an Energy-Efficient Economy Home Page (ACEEE, 1999)
Making Business Sense of Energy Efficiency and Pollution Prevention, The
Integrated Approach: Case Studies Available at:
http://www.aceee.org/p2/p2cases.htm#decatur (Last accessed, August 1999).
AuditAir (1999) The Real Cost of Air Leaks, http://www.auditair.com/cost.htm,
visited 28/6/99.
Beneficial Use Information Centre (BUIC, 1999), The University of Wisconsin-
Madison USA Available at: http://geoserver.cee.wisc.edu/buic/ (Last accessed,
August 1999).
Bremen Institute of Industrial Technology and Applied Work Science (BIBA,
1998), Rapid Prototyping Internet Site, http://www.biba.uni-
bremen.de/groups/rp/rp_page.html (Last accessed, August 1999).
Brown, J (1994), Foseco Foundryman鈥檚 Handbook, Tenth Edition, Foseco
International Ltd., UK.
Cast Metal Coalition (CMC,1998), Metalcasting Industry Technology Roadmap,
Sponsored by the CMC or the American Foundrymen鈥檚 Society, North America
Die Casting Association and Steel Founders鈥? Society of America, January.
Clegg, A., (1991) Precision Casting Processes, Loughborough University of
Technology, Leicestershire, UK, Pergamon Press, Oxford.
Commonwealth of Australia (CoA, 1985), Australian Ferrous Foundry Industry,
Final Report, Department of Industry, Technology and Commerce in
association with the Metal Trades Industry Association, October.
CRC for Alloy and Solidification Technology (CAST, 1999), Corporate
Homepage, http://mama.minmet.uq.edu.au/cast/service.html (Last accessed,
August 1999).
Department of the Environment, Transport and the Regions (DETR, 1999),
Achieving High Yields in Iron Foundries, Good Practice Guide No 17,
developed in conjunction with The Castings Development Centre.
Dr. A. Dolenc, An Overview Of Rapid Prototyping Technologies In
Manufacturing, Institute of Industrial Automation, Helsinki University of
Technology. Available at: http://www.cs.hut.fi/~ado/rp/rp.html (Last accessed,
August 1999).
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Durham M., and T. Grimm (1996) SLS and SLA: Different Technologies for
Different Applications, Prepared by Accelerated Technologies, Inc. USA, April.
Energy Saving in Foundry Services, Good Practice Guides
http://www.etsu.com/eebpp/html/snfstack_9.html
Environment Canada (1997) Technical Pollution Prevention Guide for
Foundries in the Lower Fraser Basin of British Columbia, Fraser River Action
Plan, Prepared by Kent Engineering Ltd. West Vancouver, B.C. for the
Environmental Protection Fraser Pollution Abatement Office, North Vancouver,
March 1997.
Environmental Technology Best Practice Program (ETBPP, 1995), Chemically
bonded sand: use and reclamation, prepared by Castings Technology
International.
Environmental Technology Best Practice Program (ETBPP, 1995b), Foundry
greensand: use and reclamation, Guide EG5, prepared by Castings
Technology International.
Environmental Technology Best Practice Program (ETBPP, 1995c), Saving
money through waste minimisation and reducing water use, prepared by
Castings Technology International.
Environmental Technology Best Practice Program (ETBPP, 1998), Cost-
effective management of chemical binders in foundries, Guide GG 104,
prepared by The Castings Development Centre.
Environmental Technology Best Practice Program (ETBPP, 1998b), Optimising
sand use in foundries, Guide GG 119, prepared by The Castings Development
Centre.
Foundry Online (1999). Moulding and Casting Processes, Available at:
http://www.implog.com/foundry/foundvpr.htm (Last accessed, August 1999).
Foundry Trade Journal (FTJ, 1996a), Electric ladle heater saves energy and
triples ladle lining life, Vol. 170, Number 3514, January, p 26.
Foundry Trade Journal (FTJ, 1996b), End-of-pipe abatement or process
change? The case of cupola melting, Vol. 170, Number 3514, January, p 34-38.
Foundry Trade Journal (FTJ, 1996c), Energy Saving for the 21st Century, Vol.
170, Number 3514, January, p 39.
Foundry Trade Journal (FTJ, 1996d), Rayne Foundry - where an improved
environment didn鈥檛 cost more, Vol. 170, Number 3515, February, p 64.
Foundry Trade Journal (FTJ, 1996e), Metal yield improvements, Vol. 170,
Number 3516, March, p 83.
Foundry Trade Journal (FTJ, 1996f), Electricity and metal processing - a world
view, Vol. 170, Number 3516, March, p 86-88.
Foundry Trade Journal (FTJ, 1996g), Why automate the fettling shop?, Vol.
170, Number 3516, March, p 108-110.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Foundry Trade Journal (FTJ, 1996h), Profit from water based investment, Vol.
170, Number 3517, April, p 136-137.
Foundry Trade Journal (FTJ, 1996i), Three into one will go, Vol. 170, Number
3518, May, p 180.
Foundry Trade Journal (FTJ, 1996j), Three strand investment savers money,
Vol. 170, Number 3518, May, p 182.
Foundry Trade Journal (FTJ, 1996k), From grand scale 鈥? to door to door, Vol.
170, Number 3518, May, p 182.
Foundry Trade Journal (FTJ, 1996l), Hops makes 拢18,000 water saving, Vol.
170, Number 3522, September, p 442.
Foundry Trade Journal (FTJ, 1996m), Sand mixer control for the future, Vol.
170, Number 3522, September, p 451.
Foundry Trade Journal (FTJ, 1996n), Longer life for shell patterns, Vol. 170,
Number 3523, September, p 470.
Foundry Trade Journal (FTJ, 1996o), The taxing problem of waste sand
disposal, Vol. 170, Number 3525, December, p 580-582.
Foundry Trade Journal (FTJ, 1997a), Foundry waste halved, Vol. 171, Number
3526, January, p 2.
Foundry Trade Journal (FTJ, 1997b), Energy saving - complicated arithmetic
but always positive answers, Vol. 171, Number 3527, February, p 69-70.
Foundry Trade Journal (FTJ, 1997c), Integrated system optimises production
scheduling and controls energy costs, Vol. 171, Number 3527, February, p 76.
Foundry Trade Journal (FTJ, 1997d), Foundries - Focus on Quality and Yield,
Vol. 171, Number 3528, ETSU Supplement, March, p s8-10.
Foundry Trade Journal (FTJ, 1997e), Optimising furnaces - some practical
pointers, Vol. 171, Number 3528, ETSU Supplement, March, p s10-13.
Foundry Trade Journal (FTJ, 1997f), Operation zero waste, Vol. 171, Number
3531, June, p 239-241.
Foundry Trade Journal (FTJ, 1997g), How to reduce the impact of foundry
waste arisings, Vol. 171, Number 3531, June, p 242-243.
Foundry Trade Journal (FTJ, 1997h), Keeping binder waste to a minimum, Vol.
171, Number 3531, June, p 247.
Foundry Trade Journal (FTJ, 1997i), Casting simulation for the economical
methoding of steel valve body, Vol. 171, Number 3532, July, p 267-277.
Foundry Trade Journal (FTJ, 1997j), Increased profits filter through, Vol. 171,
Number 3533, August, p 349-350.
Foundry Trade Journal (FTJ, 1998a), Managing furnaces in a changing world: a
manager鈥檚 survival guide, Vol. 172, Number 3538, January, p 560-563.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Foundry Trade Journal (FTJ, 1998b), Energy Saving: Don鈥檛 neglect ancillary
services, Vol. 172, Number 3541, April, p 137-138.
Foundry Trade Journal (FTJ, 1998c), Use of production simulation in foundries,
Vol. 172, Number 3542, May, p 167-169.
Foundry Trade Journal (FTJ, 1998d), Automated blasting is foundries鈥? answer
to cost pressures, Vol. 172, Number 3542, May, p 171-172.
Foundry Trade Journal (FTJ, 1998e), Fast cleaning from new media, Vol. 172,
Number 3542, May, p 172.
Foundry Trade Journal (FTJ, 1998f), Monitoring energy saves 拢300,000, Vol.
172, Number 3543, June, p 189.
Foundry Trade Journal (FTJ, 1998g), Seminar finds solid reasons for lost foam
casting, Vol. 172, Number 3543, June, p 198-200.
Foundry Trade Journal (FTJ, 1998h), Improved automatic pouring control
system introduced, Vol. 172, Number 3543, June, p 202-203.
Foundry Trade Journal (FTJ, 1998i), What makes a good sand, Vol. 172,
Number 3545, August, p 316-317.
Foundry Trade Journal (FTJ, 1998j), Computer aided sand quality control, Vol.
172, Number 3545, August, p 320-321.
Foundry Trade Journal (FTJ, 1998k), Virtual casting - a dream come true or an
expensive nightmare, Vol. 172, Number 3544, July, p 252-253.
Foundry Trade Journal (FTJ, 1998l), Don鈥檛 be a drip! Tap into profit with water,
Vol. 172, Number 3544, July, p 281-283.
Foundry Trade Journal (FTJ, 1998m), Simulation before speculation, Vol. 172,
Number 3547, July, p 384-386.
Foundry Trade Journal (FTJ, 1998n), To combine fettling and machining is
castings - just a question of attitude?, Vol. 172, Number 3548, November, p
443-446
Foundry Trade Journal (FTJ, 1998o), Smoking can seriously damage your
wealth, Vol. 172, Number 3549, December, p 443-446
Foundry Trade Journal (FTJ, 1999a), The benefits of oxygen on cupola melting,
Vol. 173, Number 3550, January, p 19-20.
Foundry Trade Journal (FTJ, 1999b), Energy efficient furnaces, Vol. 173,
Number 3550, January, p 29.
Foundry Trade Journal (FTJ, 1999c), Natural gas, clean and less expensive,
Vol. 173, Number 3550, January, p 31.
Foundry Trade Journal (FTJ, 1999d), Getting the best from binder systems,
Vol. 173, Number 3551, February, p 27-28.
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Cleaner Production Manual for the Queensland Foundry Industry November 1999
Foundry Trade Journal (FTJ, 1999e), Every item has its place, Vol. 173,
Number 3551, February, p 29-30.
Foundry Trade Journal (FTJ, 1999f), From chips to briquets, Vol. 173, Number
3553, April, p 18.
Foundry Trade Journal (FTJ, 1999g), From waste to riches, Vol. 173, Number
3553, April, p 18.
Foundry Trade Journal (FTJ, 1999h), Green credentials make sence, Vol. 173,
Number 3554, May, p 4.
Foundry Trade Journal (FTJ, 1999i), Energy - save it don鈥檛 spend it, Vol. 173,
Number 3555, June, p 4.
Foundry Trade Journal (FTJ, 1999j), New machine for patternless production of
prototypes, Vol. 173, Number 3555, June, p 5.
Foundry Trade Journal (FTJ, 1999k), Quality control of shell systems, Vol. 173,
Number 3555, June, p 42-50.
Guides to Pollution Prevention: Metal Casting and Heat Treating Industry,
Office of Research and Development, Washington DC, September.
Hitchener Manufacturing Co Inc. Home Page (1999), Available at:
http://www.hitchiner.com/home.html (Last Accessed, May 1999)
Hurst, S (1996) Metal Casting, Appropriate technology in the small foundry,
Intermediate Technology Publications.
International Cleaner Production Information Cleaning House (ICPIC,1999)
International Cleaner Production Information Clearinghouse (ICPIC, 1999),
Available at: http://www.unepie.org/icpic/menu.html (Last accessed, August
1999).
ISCCO Home Page (1999) Available at:
http://www.iscco.com/Technical/technical.html (Last accessed, July 1999).
Jain, P. J., (1986), Principles of Foundry Technology, Second Edition, TATA
McGraw-Hill Publishing Company Limited.
Larsen E.D., D.E. Clark, K.L. Moore, P.E. King, (1997) Intelligent Control of a
Cupola Furnace, Idaho National Engineering Laboratory (INEL), the U.S.
Department of Energy Albany Research Center, and Idaho State University.
Available at: http://www.abptuf.org/T2007/papers/adv/docs/intell.htm (Last
accessed, August 1999)
Luther, N (1999), Metalcasting and Moulding Processes, Luther & Associates, ,
Available at: http://www.castingsource.com/articles/moulding_process.asp (Last
accessed, August 1999))
MAGMA Corporation Home Page (1999) Available at:
http://www.magmasoft.com (Last accessed, August 1999).
Page 14
Cleaner Production Manual for the Queensland Foundry Industry November 1999
Metal Casting Technology Center (MCTC, 1995), What鈥檚 the best way to fill the
mold?, University of Alabama, National Metal Casting Research Newsletter,
Vol. 10 No. 1 Spring.
Metal (1996a), AW Bell鈥檚 RGS430 rapid grinding system, Vol 42, Number 5 & 6,
May/June, p 40-41.
Metal (1997a) Selecting a refractory: the first step, Vol 43, Number 7 & 8,
July/August, p 30-31.
Metal (1997b) Casting and Surface Finishing Journal, KALPUR ST - 鈥楾he
Revolution鈥?, Vol 43, Number 9 & 10, Sept/Oct, p 10-11.
Metal (1997c) Casting and Surface Finishing Journal, Pouring ladles, Vol 43,
Number 10 & 11, Nov/Dec, p 16-20.
Metal (1998a) Casting and Surface Finishing Journal, A review of current and
new riser sleeve technology, Vol 44. Number 5&6, June, p 13-18.
Metal Asia (1998a) Casting and Surface Finishing Journal, Meeting your
foundry needs with an induction melting furnace, Vol 5. Number 3, February, p
13-18.
Metal Asia (1998b) Casting and Surface Finishing Journal, Pouring ladles, Vol
5. Number 3, April, p 19.
Metal Asia (1998c) Casting and Surface Finishing Journal, How to Minimise
Lining Wear when Melting Iron in Coreless Induction Furnaces, Vol 5. Number
6, October, p 18-20.
Metal Asia (1998d) Casting and Surface Finishing Journal, Casting Simulation:
Practical Considerations for the Average Foundry, Vol 5. Number 6, October, p
22-25.
Metal Asia (1999a) Casting and Surface Finishing Journal, Rapid Prototyping,
Recent Developments for Foundry Applications, Vol 6. Number 2, February, p
20-24.
Metal Asia (1999b) Casting and Surface Finishing Journal, Direct Pour - A
Reality, Vol 6. Number 3, April, p 12-15.
Metal Asia (1999c) Casting and Surface Finishing Journal, The Basics of
Foundry Melting Processes, Vol 6. Number 3, April, p 24-27.
Minnesota Technical Assistance Program (MNTAP, 1994) Aluminum Foundry
Replaces TCA with Water-based Coatings, Available at:
http://www1.umn.edu/mntap/P2/FOUND/cs93-e1.htm (Last accessed, August
1999).
Ohio Environmental Protection Agency (OPEA, 1998), Governor's Pollution
Prevention Award Recipient - Ashland Chemical Company Foundry Products
Division, Office of Pollution Prevention, Fact Sheet Number 54, March,
Available at: http://www.epa.state.oh.us/opp/gov/fact54.html (Last accessed,
August 1999).
Page 15
Cleaner Production Manual for the Queensland Foundry Industry November 1999
Powell J. (1992) 'The effective control of electricity use in melting and holding
furnaces'. The Foundryman Volume 83 Part 7 pages 314-326.
Quality (1996) Automated pouring saves $1 million, vol 35 no 1, January, pp.
44-46.
Quality (1996) Precise pouring aids production, vol 37 no 1, January, pp. 54-55.
Queensland Government Environmental Protection Authority (EPA, 1999),
Environmental Guideline: Beneficial re-use of ferrous foundry by-products -
draft guidelines.
Queensland Manufacturing Institute Ltd (QMI, 1998), Corporate Homepage,
http://www.qmi.asn.au/home.html (Last accessed, August 1999).
Signicast Corporation Home Page (1999) Available at:
http://www.signicast.com/reinvent.html (Last accessed, July 1999).
Solid Concepts (1997)SLA Rapid Prototypes, Accurate models and patterns at
competitive prices, Process Fact Sheet, August.
Steel Founders' Society Of America (SFSA, 1999) Glossary of Foundry Terms,
Available at: http://www.sfsa.org/glossary/cstgloss.html (Last accessed,
October 1999).
Taft, R. T, (1995) High Technology Melting, Technical Documentation,
Cokeless Cupolas Limited, United Kingdom Available at:
http://www.cokeless.co.uk/index.html (Last accessed, August 1999).
The Foundryman (1996a), The replacement of solvent based coatings in
modern foundries, The journal of The Institute of British Foundrymen, Vol 89,
Number 9, September, p 287-290.
The Foundryman (1997a), Metal quality and reliability: realising cost savings
and environmental benefits, The journal of The Institute of British Foundrymen,
Vol 90, Number 3, March, p 72-77.
The Foundryman (1997b), Progressive management in a batch producing SME
foundry: Accrue big benefits without incurring big costs, The journal of The
Institute of British Foundrymen, Vol 90, Number 5, May, p 164-165.
The Foundryman (1997c), Hadleigh, where the concept of sand conservation
has become a reality, The journal of The Institute of British Foundrymen, Vol
90, Number 7, July, p 252-254.
The Foundryman (1997d), Is your foundry using too much juice, The journal of
The Institute of British Foundrymen, Vol 90, Number 12, December, p 431-432.
The Foundryman (1998a), Training in energy Efficiency as a part of continuing
Professional Development, The journal of The Institute of British Foundrymen,
Vol 91, Number 7, July, p 219-222.
The Foundryman (1999a), Training can cut blasting costs, The journal of The
Institute of British Foundrymen, Vol 92, Number 1, January, p 6.
Page 16
Cleaner Production Manual for the Queensland Foundry Industry November 1999
The Foundryman (1999b), Lower costs from reduced packaging, The journal of
The Institute of British Foundrymen, Vol 92, Number 1, January, p16-17.
UNEP (1997) Cleaner Production in Foundries, Industrial Sector Guide, Danish
Environmental Protection Agency in cooperation with CPWI Consulting
Engineers and Planners, February.
United States Environmental Protection Agency (USEPA, 1998), Sector Note
Book: Profile of the Metal Casting Industry, Office of Compliance, Washington
DC, February.
The University of Sheffield Thixoforming Group (THRUST, 1997), The
Thixoforming Homepage, Available at: http://www.shef.ac.uk/uni/academic/D-
H/em/SSM/index.html (Last accessed, August 1999).
Waste Management Co Homepage (WMC, 1999) Cleaner Production Case
Studies Available at: http://www.waste-management.co.uk/studies/ashley.htm
(Last accessed, June 1999).
Worchester Polytechnic Institute (WPI, 1997) Semisolid Material Processing
Laboratory, Available at:
http://www.wpi.edu/Academics/IMS/Research/MPI/ssmp.html (Last accessed,
August 1999).
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