ENVIRONMENTALLY CONSCIOUS MANUFACTURING

Selection of Processes to Support Environmentally Conscious Design and Manufacturing

Industrial Design for Environment Via Design for Disassembly - An Automotive Focus

Goal: The overall goal of this project is to develop environmentally conscious design and manufacturing tools and methods that will help alleviate the abundance of waste associated with used product and manufacturing waste streams.

Rationale: The impetus behind this project is the increase in residential and industrial waste in the U.S. This project is focused on determining ways to reduce or end waste at both the design and the manufacturing stages of a product. The product designer's job is to create a product that meets the requirements of form, fit, and function, but, generally with little consideration for the product's disposition after its intended usefulness has been exhausted. By consideration of this issue during product design, it may be possible to extend its useful lifetime through secondary uses. Where this is not possible, it may be possible to better prepare the product for reuse and recycle through activities such as designing the product for inexpensive and efficient disassembly. In addition to this, largely post-consumer aspect, an understanding of waste streams produced during product manufacturing can result in identification of wastes which can be avoided or reduced.

Approach: Under the broad umbrella of Environmentally Conscious Design and Manufacturing, several initiatives have been undertaken to meet the goal. Environmentally conscious design focusses efforts on determining product design specifications, developing and analyzing design features, and evaluating costs and benefits. The evaluation of these factors will lead to useful pollution prevention methodologies. Models for design effort distributions, environmental cost drivers, and part shape are being created to evaluate a product's environmental consciousness. This work, in conjunction with Rajit Gadh at UW, will create specific computer algorithms and tools that aid in making environmental design decisions.

Environmentally conscious manufacturing issues are also being looked at in several areas. By developing a complete understanding of how machining and manufacturing processes work, their waste streams can be minimized. Efforts under this project are focused on understanding the role of cutting fluids in various machining processes, such as turning, milling, boring, and drilling. Experiments are being run and analyzed so that models can be created that describe the effects of cutting fluid. Such results will provide manufacturers with information about the cutting fluid and its necessity. Other considered components of manufacturing process waste streams will include: chips, heat generation, and machine tools. The outcome from both the design and manufacturing focus will be provided to others through computer tools and models. This knowledge can then be used in conjunction with existing technology to help reduce the waste stream from both product and process.

Status: The accomplishments of this project thus far have been quite significant in defining the direction of Environmentally Conscious Design and Manufacturing. A list of important environmental design specifications was established from the physical disassembly of Whirlpool washing machines. These specifications, some obvious and some subtle, include: reduce the number of parts, reduce the number of materials, code and mark all parts, use features that promote disassembly, avoid contaminating and coating of material, and modularize components. Upon compiling this list, an effort was undertaken to create a hierarchical structure that ranks design factors with possible post-use processes. The essential design factors used are time, cost, materials, energy, and modularity. The post-use processes are reuse, recycle, remanufacture, and disposal (demanufacturing). The hierarchy was established to determine where the most design effort should be focused to achieve one of the desired post-use processes (reuse, recycle, or remanufacture).

Building on the Whirlpool effort has resulted in a more specific focus on discrete products. An index system that characterizes the remanufacturability or reprocessability of a specific part has been created. The Reprocessability Index (RPI) is a metric that characterizes parts by their shape, features, volume, and stress. The RPI provides an understanding of how physical properties affect environmental impact. It is believed that volume of the part and specific features within the part are large factors that will affect the post-use life of the part. The initial work has been done through AutoCad and the application of an AutoLisp program.

Another software tool was created that examines the life cycle assessment (LCA) of automobile bumpers. An Excel based program was developed to analyze costs associated with the entire life cycle of the bumper. Other design effort work looked at how loss functions and value functions capture the costs/benefits of demanufacturing.

The work done in the environmentally conscious manufacturing has produced results, some of which are being exploited by industry. The use and role of cutting fluid in machining operations has become better understood. It was found that the fluid was not a significant factor in the boring of aluminum alloys, but it is becoming evident that the fluid does have an effect in small diameter drilling. Currently, much of the data from preliminary drilling experiments is being analyzed. Studies are also being conducted to understand the costs of the waste stream. It is believed that the major expense in the waste stream is the handling of cutting fluids. Therefore, the elimination of them would prove both economical and environmental.

The reduction of automobile shredder residue (ASR) was another important manufacturing system focused on. Experiments and models were created to simulate the shredding of various plastics and produced methods to shred the plastics.

Industrial Design for Environment Via Design for Disassembly - An Automotive Focus:

Goal: To research and develop a design for disassembly technology so that products, such as automobiles, may be disassembled and their components reutilized or recycled. This would facilitate Design-for-Environment (DFE) technologies in product design and manufacturing.

Rationale: Given that the emphasis on recycling products is only going to increase in the future, it is important that organizations start becoming conscious of the need to design products that are environmentally friendly, despite the belief that this will significantly increase their design and manufacturing cost. The Principal Investigator (PI), Rajit Gadh, believes that this belief is not necessarily true for several reasons. First, through the use of computer tools, products may be analyzed for environmental friendliness as well as for functionality, manufacturability, strength, etc. In the long run, automated computer-based tools can make this activity economical. Second, the extra effort in designing environmentally friendly products is often not significantly more than designing for other considerations - in fact, often a minor design change is sufficient to make a product environmentally friendly. Third, several companies, such as Digital Equipment Corporation, are buying back their products at the end of the product's life cycle. They are able to disassemble the products into individual components, and even make a profit selling these recycled components. Fourth, companies that invest in research and development efforts in designing environmentally friendly products typically qualify for governmental rebates and subsidies, which could help pay for their DFE efforts. Finally, an environmentally friendly product will cause less damage to the environment, resulting in less chance of a lawsuit against the manufacturer. Therefore, if done right, DFE could be considered an opportunity from which manufacturing companies could actually profit, rather than lose money.

Approach: The Design-for-Environment (DFE) methodology employed in the current research to products, such as automotive sub-assemblies (e.g., engines), can assist companies in becoming better believers in the importance and practicality of this field. The software resulting from this methodology will allow users to input product designs, and will inform them of potential environmental problems associated with the disassembly of this product. It will do this in a variety of ways, the principal one being the ease of disassembly of this product. If a product can be easily disassembled, its components can be recycled. If some of the components are not disassemblable, a destructive technique will be needed that will destroy one or more components so that the others can be disassembled and therefore recycled. In this situation, it may still be possible to save some of the more expensive components by destroying the cheaper ones, such as assembly screws. Deciding which components to destroy and the mode of destruction is critical in this step.

Status: A version of the non-destructive disassembly technique has been developed for theoretical cases. It is currently being implemented on the computer. Its practical examples are also being studied, and some of its assumptions have been found to restrict the cases which it can handle. These cases are being studied and the non-destructive algorithm is being reassessed as it is used in DFE.

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