Influence of computer chassis design on metal fabrication waste streams

There is growing interest in studying the influence of design decisions within a product life cycle, especially in designing for ease of disassembly and recycling. However, a significant life-cycle component of the wastes associated with the product occur at the primary manufacturing stages. This paper examines the environmental impact of chassis design features on process flow for metal fabrication. Critical processes include blanking, punch, metal deformation , finishing and welding. The availability of data at several levels of aggregation is supplemented by the development of analytical models of process physics to derive a process-level inventory of energy utilization, primary scrap and secondary catalysts (tool, fluid and vapor waste streams). The mass flows of waste streams can be weighted by impact on factors such as toxicity, carcinogenesis, reactivity, flammability, and irritation using material safety data and survey of site-specific factors. A case study of a chassis assembly for a network server is presented with several design alternatives to illustrate the impact of feature changes and component consolidation on waste streams. The trade-offs between environmental, manufacturing and product performance factors are discussed.