conscious coatings for sand/permanent molds, new binders and lost foam ... Free form manufacturing offers more potential environmental benefit than P/M, eliminating the need for dies ... Inspection. Use Phase ..... Albuquerque, NM, Feb. 12-15.
ENVIRONMENTALLY BENIGN MANUFACTURING: STATUS AND VISION FOR THE FUTURE
J. W. Sutherland, K. L. Gunter, K. R. Haapala, and K. Khadke Dept. of Mech. Engr.-Engr. Mechs. Michigan Technological University
S. J. Skerlos and J. B. Zimmerman Dept. of Mech. Engr. University of Michigan
W. W. Olson and R. Sadasivuni Dept. of Mech., Ind., & Manf. Engr. University of Toledo
ABSTRACT Results from a National Science Foundation sponsored workshop on Environmentally Benign Manufacturing (EBM) in the Transportation Industries are described. This workshop was organized through the leadership of the NAMRI/ SME community and builds on the results of a worldwide benchmarking study supported by NSF [Gutowski, et. al., 2001]. The workshop was focused on identifying strategic directions, issues of importance, and EBM research topics. Experts in Metals Processing, Non-Metals Processing, Product Design and Support, and Enterprise and Factory Operation discussed the future of EBM and contributed valuable suggestions/comments.
INTRODUCTION The environment is an ever-increasing priority for many corporations and the acronym EBM (Environmentally Benign Manufacturing) has been adopted to describe a philosophy that minimizes manufacturing environmental impacts. In a narrow sense EBM calls for green manufacturing processes, but more broadly calls for corporate-wide environmental improvement. Interest in environmental issues within the
NAMRI/SME research community started in the early 1990s, and by the end of the decade had grown enough to warrant the formation of an EBM working group. The members of this group have included D. Durham, R. Furness, J. Jeswiet, S. Liang, W. Olson, P. Sheng, S. Skerlos, and J. Sutherland. Recognizing the need to understand the state-ofthe-art with respect to EBM, the National Science Foundation (NSF) funded an Environmentally Benign Manufacturing (NSF-EBM) global benchmarking study in 1999-2000. A total of 52 different locations in the U.S., Northern Europe, and Japan were visited by an interdisciplinary panel. Japan and Northern Europe were included in the benchmarking because of their leadership in environmental issues, high population densities, and high per capita GDP (gross domestic product); these last two factors generally indicate the potential for environmental problems and the resources to address them. The panel consisted of T. Gutowski, C. Murphy, D. Allen, D. Bauer, B. Bras, T. Piwonka, P. Sheng, J. Sutherland, D. Thurston, E. Wolff, D. Durham, K. Rajurkar, and F. Thompson. The focus of the global benchmarking panel was on the entire manufacturing enterprise (e.g., design, production, and administration), but
emphasis was placed on metals and polymer processing in two key industrial sectors automotive and electronics. To organize panelists’ thinking and acquire structured information, the following general types of information were sought during the visits to companies and research labs: • National level strategies being undertaken, • Corporate level EBM motivation factors, • Examples of systems-level problem solving or systems-level EBM issues, • Analytical tools for addressing EBM products and processes, and • Technology highlights. Based on the technical literature and the information acquired from all the site visits, a report was prepared to document the opinions and findings of the panel [Gutowski et al., 2001].
and Enterprise and Factory Operations. The findings/opinions of the workshop groups are presented in the next several sections. TABLE 1. GOVERNMENT ACTIVITIES* Japan
U.S.
Europe
Take-back legislation
Activity
**
*
****
Landfill bans
**
*
***
Material bans
*
*
**
***
**
****
LCA tool and database development Recycling infrastructure
**
*
***
Economic incentives
**
*
***
Regulate by medium
*
**
*
Cooperative/ joint efforts with industry
**
*
****
Financial and legal liability
*
****
*
* Asterisks indicate relative strength, and are intended to be indicative of level of emphasis as much as actual level of success.
TABLE 2. INDUSTRIAL ACTIVITIES Activity
Building on the global benchmarking study and under the leadership of the NAMRI/SME community, an NSF sponsored three-day workshop on EBM was held during September 2001 in Ypsilanti, Michigan to identify key EBM challenges and provide a vision for the future especially as it relates to the automotive/ transportation industry. The workshop organizers included: J. Decaire, R. Furness, S. Liang, R. McCune, R. Neal, W. Olson, S. Skerlos, and J. Sutherland. The 60 workshop attendees were divided into 4 groups: Metals Processing, NonMetals Processing, Product Design and Support,
Japan
U.S.
Europe
****
*
***
**
***
*
****
**
**
Decreased releases to air and water
*
***
**
Post-industrial solid waste reduction
****
**
*** ****
ISO 14000 certification Water conservation Energy conservation/ CO2 emissions
Post-consumer recycling
**
*
Material and energy inventories
***
*
**
Alternative material development
**
*
***
Supply chain involvement EBM as a business strategy Life cycle activities
**
*
**
****
**
***
**
**
**
TABLE 3. RESEARCH/DEVELOPMENT ACTIVITIES
Basic Research
Activity
Applied Research
A key finding was that business needs and cultural/geographic differences strongly influence the environmental focus in each region, making direct comparisons rather challenging. The focus noted for each region was as follows: • U.S. is involved in avoiding fines/litigation, and employing non-hazardous materials and cleaner manufacturing processes. • Japan is focused on incorporating EBM principles into their business operations, with a principal goal being resource conservation. • Northern Europe is concerned with product end-of-life, recycling infrastructure, and eliminating hazardous materials. It was also noted that the driver for EBM in the U.S. is cost, while Europe/Japan view it more as a societal concern and look for solutions via systems thinking. The study concluded that the U.S. lags Japan and Northern Europe in terms of most EBM-related activities. Tables 1-3 summarize the differences in key categories.
Japan
U.S.
Europe
Polymers
**
***
**
Electronics
**
***
*
Metals
***
*
**
Automotive/Transportation
**
*
***
Systems
**
*
***
Polymers
*
***
**
Electronics
***
**
**
Metals
***
*
**
Automotive/Transportation
***
*
***
Systems
**
*
***
METALS PROCESSING In spite of the increased use of plastics in automobiles, the metal mass fraction of an average U.S. vehicle is approximately the same today as it was in 1980 (Graedel and Allenby, 1998). The Metals Processing group concluded that over the course of the next several decades metals will continue to play an important role in the transportation industry. The findings of the
group have been organized according to the life cycle stages of a product shown in Figure 1, and are further discussed below. The figure also summarizes the EBM research priorities with respect to metals processing.
Metals Design Cost Performance Recycling
Primary Operations Extraction Beneficiation Casting
End of Life Disassembly Reuse/ Recycling Inspection
Use Phase Mass-Propulsion Inspection
Manufacturing Metalworking PM/Free Form Finished Surfaces
Assembly Joining Inspection
Cross-Cutting Issues Education, Energy, Environmental Priorities, Design Tools, Consolidation, Elimination and Hybridization of Operations
TOP RESEARCH PRIORITIES Net shape casting Effluent free machining Life cycle system design - Materials, material selection, manufacturing, recycling - Design alloys for performance, cost, processing, EBM Minimize air emissions and energy in joining Improve knowledge of engineering surface processes Minimize molding materials and air emissions in casting Facilitate end of life disassembly
1. LIFE CYCLE ISSUES & RESEARCH PRIORITIES FROM METALS PROCESSING GROUP
Metal Design/Selection. Traditionally, metal alloy design has aimed at optimizing the use phase of the life cycle (e.g., optimizing strength). Therefore, one research need is to also include the manufacturability, recyclability, and total life cycle cost of engineered alloys. Contrary to the trend toward higher specificity (greater variety) in metal alloy design, the recycling of metal alloys at the end-of-life (EOL) suggests a need for more universal alloy design (less variety). Alloy design for EBM also calls for facilitating identification, separation, and purification to permit these alloys to be truly recycled rather than down-cycled. Clearly, material design and selection decisions would benefit from development of streamlined/ tailored life cycle analysis methodologies. Primary Processing and Casting. A significant reduction in pollution due to mining and beneficiation would result from higher metal recycling/reuse rates. This would also reduce the energy consumption during purification. Robust aluminum recycling processes were singled out as an important means to achieve this end.
Improved net shape casting would result in less downstream waste. Casting advances may be facilitated by improved prediction of mold distortion via modeling/simulation and on-line process control via integrated sensing technology. Environmental improvements in casting would result from environmentally conscious coatings for sand/permanent molds, new binders and lost foam materials with minimal VOC (volatile organic compounds) emissions, improved thermal management for reduced energy consumption (and heat reclamation), and integrated heat treatment/casting. Metalworking. The most important area for improvement in metalworking was considered to be coolants and lubricants (metalworking fluids or MWFs). It was concluded that MWF-related environmental improvements should include: • Net shape operations that eliminate the need for metalworking operations and tool-less forming (e.g., laser processing). • Development of dry machining technology or integrated die coatings that avoid MWFs. • When MWFs are needed, minimize volumes, improve MWF recycling technology, and control MWF mists to reduce health hazards. Several other research areas were identified: CAD-based process planning to minimize scrap and energy consumption, reconfigurable machine-tools to limit scrapping of production lines at their EOL (also reconfigurable dies), improved technology for recovery and recycling of scrap metals generated during metalworking. P/M and Free Form Manufacturing. Powder metallurgy (P/M) and free form manufacturing lead to the elimination of casting, forging, and machining operations. However, technological improvements to these processes are required to increase production rates, improve applicability to common materials, eliminate existing tradeoffs between part complexity and size, and improve surface properties and strength. It was concluded that P/M processing environmental issues need to be addressed (e.g., sintering energy consumption and toxic binders). Free form manufacturing offers more potential environmental benefit than P/M, eliminating the need for dies, compaction, and diffuse heating. Finishing Operations. Research needs identified for finishing operations, e.g., heat treatment, cleaning, and plating, were:
• Improved understanding of metalworking tribology to facilitate minimal use of lubricants upstream of finishing operations. • Low-energy processes to eliminate bulk heat treatment. • Reduced use of solvents, improved recycling rates for aqueous cleaners, increasing metal and chemical recovery from rinse waters. • Closed-loop finishing processes. Joining and Assembly. A common class of joining operations are traditional welding processes. Welding environmental concerns include hazardous fluxes, metal fumes, and energy consumption. These concerns can be reduced by minimizing the number of welds in a product, facilitated by structural modeling and optimization tools. More benign alternative welding processes should also be investigated (e.g., friction stir welding). In general the environmental impact of joining processes can be minimized by upstream net shape processes. Reversibility of permanent joints should also be examined since permanent joints limit the potential for product disassembly (component recovery. Inspection. Research needs for inspection (e.g., part dimension evaluation, texture assessment, and surface integrity appraisal) include: • Reducing scrap via better product quality and fault identification technologies (e.g., simulation-based process control, AI-based imaging systems). • Enhancing inspection methods, perhaps based on acoustics or laser surface excitation, that avoid problems of traditional surface integrity measurement methods employing toxic fluorescent penetrants. • Developing product-integrated sensors to replace traditional inspection and quality evaluation methods. Cross-Cutting Issues. The group identified several topics beyond the scope of the life cycle stages. These cross-cutting need areas include: • A national environmental strategy to set priorities for improvement efforts. • Meaningful life cycle design tools and supporting data that can be used by product/ process designers. • Manufacturing process consolidation and hybridization to reduce environmental impact and cost.
• Analysis of increasingly decentralized supply chain relationships in the transportation/ automotive industry. The group also noted that engineering education should place greater priority on the environment.
NON-METALS PROCESSING Non-metals such as glass, plastics, ceramics, and composites are being ever more widely used in transportation-related products. The NonMetals Processing group discussed two facets of this field - materials and processing (Fig. 2) - to define new research areas. In terms of environmental issues, machining, assembly/ joining, and coating/painting are the most important process areas, followed by molding, extrusion, and cleaning.
EBM Usage of Non-metals in the Transportation Industry Materials * Widen spectrum of properties and improve performance * Optimize material use * Reuse discarded materials * Use more recycled materials * Increase use of biomaterials * Reduce materials constituting a product * Self curing coatings and improved treatment technology for coatings * Materials resistant to UV rays, additives and chemicals
Processing * Lower environmental impact * Design and manufacture for easy assembly, disassembly, and recycling * Reduce processing steps * Analyze tools for optimization of processing * New, longer lasting coatings for tools * Near net-shape processing (e.g., for ceramics) * Miniaturization and micromanufacturing
Research Needs * Base use decision on complete LCA * Develop smart capabilities in materials and processes * Develop comprehensive databases * Minimally tweak present procedures in development of completely new methods (predictable EBM) * Facilitate maximum material separation in recycling * Increase instrumentation and automation of processes * Develop and increase use of better simulation methods * Investigate and use bio-mimicry to create new materials according to a plan or pattern
2. ISSUES AND RESEARCH PRIORITIES FROM NON-METALS PROCESSING GROUP
Materials Polymers and composites have to be made more long lasting, and either recyclable or biodegradable at the end of a use cycle. Resins used in manufacturing have no VOCs (volatile
organic compounds), HAPs (hazardous air pollutants), heavy metals, or black-listed components. The ability to crack polymers into monomers for reuse would be very beneficial. New glass and ceramic materials are needed with enhanced properties. Materials that are robust to contaminants and that do not require manufacturing lubricants are also desired.
Cleaning fluids used in conjunction with nonmetals need to be made long lasting and environment friendly. Ideally, strategies should be developed to eliminate cleaning operations, or at least be effluent-free. In the short term, cleaning wastes must be captured and effectively treated/handled, and mechanisms associated with the various cleaning methods understood in detail.
Processing PRODUCT DESIGN AND SUPPORT Better modeling and simulation tools have to be developed and used to create simpler and cleaner operations. New processes should be sought that are robust, energy-efficient, automated, and self-optimizing. Strategies are needed to combine/hybridize processes, along with improved process control and continuous rather than batch production. Molding and extrusion methods have to be developed to enable the manufacturing of complete, complicated parts in one step. New processes may be necessary to work with new types of materials (e.g., foams) having desirable properties (e.g., thermal and shock absorption). The machining of polymers has several research needs. These include: longer lasting cutting tools, dry machining, and simulation tools to select process conditions that avoid thermal distortion, cutter breakage, and dynamic instabilities that may lead to scrap parts. To reduce the impact of assembly and joining the following areas of research were identified: • Develop new methods for joining. • Methods to decrease the number of joints. • Adhesives that are environmentally benign and permit product disassembly. Finally, research is needed on smart joints that indicate (e.g., change color) imminent failure.
The Product Design and Support (PDS) group identified the need for a comprehensive, analytical, and user-friendly design tool to incorporate life cycle considerations into the design process. As shown in Figure 3, this goal requires research in several key areas: i) life cycle assessment, ii) materials and manufacturing, iii) design for the environment, iv) system issues. These areas are further discussed in the following paragraphs.
LCA & Eco-Design Optimization Support •Life Cycle Scope & Procedure •Data Quality & Availability •Environmental Priorities & Optimization Procedures
Design for Environmentally Benign Materials Selection & Manufacturing •Materials Selection •Process Selection
DESIGN FOR EBM IN THE TRANSPORTATION INDUSTRY System Issues in Design for Environment •Communication •EBM Technology Diffusion •Eco-Drivers
Design for Environment During Use & End-of-Life •Modular Design •Handling at End of Life •Supply Chain & Infrastructure
3. ISSUES IDENTIFIED BY THE DESIGN AND SUPPORT GROUP
PRODUCT
Life Cycle Assessment Coating and painting processes require more energy efficiency and improved reduction (and capture) of environmental emissions. The need for coating processes could be reduced by incorporating an equivalent function into an uncoated product. Self-curing coatings that require minimal processing should be developed, as well as methods to build a wide spectrum of color/finish/function into products. The VOC content of paints should also be reduced.
To date, performing detailed life cycle inventories (LCI) has proven difficult in the transportation industry, as well as relating LCIs to a defendable impact analysis and translating the results into appropriate action [Frosch, 1995]. As such, the following research needs were identified. Scope and Procedure. Environmental impact analyses performed as part of an LCA are
sensitive to a variety of assumptions and metrics. The PDS group advocated: • Research to identify the most appropriate allocation schemes in LCAs, • Development of guidelines for utilizing streamlining techniques, and • Research to compare outcomes of full and streamlined LCAs. Data Quality & Availability. The utility and conclusions of an LCA are dependent on data quality. Public databases detailing environmental impacts of materials and processes have helped to reduce LCA costs, but bring with them accuracy, consistency, and precision concerns. This drives the following needs: • Improvement of existing databases by improving data quality and identifying/filling data gaps, • Verification of LCA data repeatability, and • Quantification of uncertainties and risks. Environmental Priorities. The ability for an LCA to predict actual impacts on human health, environmental quality, and resource depletion is challenging [Keoleian, 1995]. Outputs can be allocated by magnitude of impact, sensitivity of system impacted, and toxicity associated with the impact. Research demands are then: • Resolve how environmental impacts should be weighted relative to one another, and • Develop trade-off analyses (including multicriteria decision-making techniques) to achieve eco-design optimization.
Materials and Manufacturing Material selection and manufacturing planning are key elements of the design process, and therefore have a significant influence on the ability of any industry to achieve EBM. Research needs in these areas are described below. Materials Selection. To select environmentally benign materials, a significant amount of data (e.g., quantity of raw materials/energy consumed and quantity of pollutants). Currently, these data are scarce, and existing data have not been analyzed for their quality, leading to the following investigation areas: • Standardized data set of material properties, especially for recycled materials, • CAD systems with material data (information
on properties such as recyclability, biodegradability, and material toxicity), and • Engineering curricula that promote design with novel, recycled, or recovered environmentally benign materials. Process Selection. The resources consumed and waste generated by manufacturing have not been well quantified. Where good data exists, it is often aggregated and difficult to trace to a single operation. To facilitate life cycle decision making, the PDS group called for: • Quantification of resource inputs and waste outputs from manufacturing processes, • Improved knowledge of how manufacturing pollutants interact with natural systems, • Consideration, at the design stage, of spatial and temporal environmental impacts, • Understand how use of environmentally benign process inputs impacts traditional manufacturing processes, and • New or modified manufacturing technologies to achieve EBM.
Design for the Environment Environmental impacts can be reduced by DFE (design for the environment), extending the useful life and facilitating the recovery, reuse, and recycling of a product at the end of its life. DFE includes: i) modular design, ii) design for post-use, and iii) supply chain changes. Modular Design. Major improvements in the environmental performance of products would result from a shift toward modular, upgradeable platforms. Research needs for this shift include: • CAD-facilitated methods that consider modular structure, delineation, and function, • Module definition across platforms and product generations that do not limit design flexibility, and • Integrated enterprise and engineering models to forecast the availability of product components and their expected condition. Design for Post-use. For modular, upgradeable platforms to become a viable EBM strategy, technologies to track, sort, and characterize recovered components are needed, including: • Technologies to track post-use modules, • Intelligent and low cost separation, sortation, and characterization technologies, including
facilitating fastener technology, and • Flexible dismantling facilities to permit disassembly of a diverse range of products. Supply Chain Changes. The development of markets for the reuse of reclaimed materials and components requires a system for handling, distributing, and reselling of recovered materials and components. It is recommended that this infrastructure move beyond a simple closed loop system to take the form of intelligent networks with multiple and migratory uses of products and modules. Manufacturers will have to look beyond their traditional supply chain for resources. To support this new expanded infrastructure, the group advocated: • The development of innovative EOL inventory management strategies, and • Information technology to track material properties, expected costs, volume demands, and location needs throughout the supply chain.
Eco-Drivers. EBM may best be promoted by establishing that EBM is more than philanthropy. Eco-drivers must be identified that link environmental performance to marketplace advantages. Furthermore, effective means and metrics are also required to communicate the importance of EBM to consumers.
ENTERPRISE AND FACTORY OPERATION The Enterprise and Factory Operations (EFO) group, identified research topics at two levels of concern as shown in Fig. 4. The topics are discussed further below.
Supply Chain Issues Workforce Issues
Enterprise Level Process Monitoring and Control
System Issues
Communication. Efficiently conducting a full LCA requires interacting with suppliers at all tier levels [Frosch, 1995]. Preserving confidentiality of proprietary data without compromising the credibility of an LCA has been identified as a major inhibitor to eco-design. Improved information systems are needed to share life cycle data horizontally/vertically across the extended enterprise via an open, practical, and information protective infrastructure. Technology Diffusion. Research needs that promote the establishment of communication channels for LCA data that facilitate the diffusion of EBM into standard industrial practice include: • Identifying and describing the effect of factors that influence (impede or promote) adoption of EBM innovations [Surry, 1997]. • Identifying technological and cultural solutions to facilitate EBM diffusion.
Policy and Economics
Factory Level Energy Management
One of the main challenges for OEMs associated with EBM is transforming product responsibility into product stewardship that extends beyond the factory. Communication, technology diffusion, and eco-drivers will facilitate this transformation.
Regulatory Management
Management Practices
Waste Management Material Control, Recycle, and Reuse
Standards and Metrics
Implementation
4. TOPICS IDENTIFIED BY ENTERPRISE AND FACTORY OPERATIONS GROUP
Factory Level Operations In terms of the Factory Level, topics discussed included: process monitoring/control, material control, recycle/reuse, and waste/energy management. Research related to process monitoring and control should focus on development of systems focused on EBMrelated issues. For recycle/reuse demands include material/product design and material selection to facilitate recycling/reuse. For waste management, research should center on eliminating waste, using wastes for other purposes, and quantifying waste impacts. For energy management, usage of secondary energy, equipment efficiency, and usage of renewable resources should be explored. Discussions by the EFO group identified four high priority research areas:
• Develop models of sectors and systems that assess, understand, and predict social, economic, and environmental impacts. • Understand resource demands and environmental impacts of automotive and other transportation products, to prioritize where improvement efforts should be placed. • Understand the relationship between EBM and bottom line related performance (cost, quality, time). • Integrate EBM into engineering/business curricula and company training programs. The last point is especially noteworthy, since real permanent change will only come through an informed populace and decision makers.
Enterprise Level Operations In terms of the Enterprise Level, a number of research demands were identified. One need that was recognized was a method to effectively measure and assess EBM metrics throughout the supply chain. Another area of discussion centered on linking purchasing decisions to environmental performance. For regulatory management in the extended enterprise, one suggested goal was to streamline regulations, and make them more standardized and sciencebased. The importance of relating EBM to the bottom line and institutionalizing it as a long-term corporate strategy was also pinpointed. Standard software, metrics, and interchangeable data-bases were recognized as enablers to the diffusion of environmental thinking across the enterprise. Workers are needed that understand and can make EBM decisions. Management practices are required that can integrate and permeate EBM practices across the organization. Research must investigate organizational information networks and ideas to enhance system behavior. Mechanisms, methods, and incentives should be identified to promote the adoption of EBM. Moreover, research should focus on effectively integrating EBM into an organization from a regulatory, policy, cultural, and strategic viewpoint.
SUMMARY A National Science Foundation workshop on Environmentally Benign Manufacturing (EBM) in
the Transportation Industries brought together sixty experts to discuss and consider future research objectives. The opinions of the participants are documented in this paper and were used to support the creation of an NSF Program focused on developing solutions to environmental problems in manufacturing [NSF, 2002]. All working groups emphasized that total life cycle analyses must be incorporated into the practice of design and manufacturing to improve the triple bottom line (social, economic, and environmental performance) of corporations.
ACKNOWLEDGEMENTS NSF (DMI-0117800) financially supported the EBM workshop. The contributions of the 60 participants are gratefully acknowledged.
REFERENCES Frosch, R., (1995), "The Industrial Ecology of the 21st Century," Sci. American, Sept., pp. 178-181. Gutowski, T., et al., (2001), Environmentally Benign Manufacturing, WTEC-Loyola College, Baltimore, MD. Keoleian, G., (1995), “Pollution Prevention through Life-Cycle Design,” Industrial Pollution Prevention Handbook, McGraw Hill, pp. 253-292. NSF, (2002), National Science Foundation PREMISE Program Solicitation, NSF-02-053, Div. of Design, Manufacture, and Industrial Innovation. Olson, W., and Sutherland, J., (2002), "National Science Foundation Workshop on Environmentally Benign Manufacturing for the Transportation Industries," SAE 2002-01-0593, Environmental Issues for the Automotive Industry, SAE Publ. SP-1672, March, 2002, pp. 19-27. Surry, D., (1997), “Diffusion Theory and Instructional Technology,” Annual Conf. of the Assoc. for Educ. Comm. and Tech., Albuquerque, NM, Feb. 12-15.
