Quantitative assessment of disassembly difficulty in product recycling

Abstract

Design of products for case-of-disassembly is a key aspect of product recycling. Similarly, design tools which allow alternative designs to be compared with respect to case-of-disassembly are of great importance. An improved method for assessing the difficulty encountered in disassembling products for recycling is presented. The original version of the method relies on the evaluator's subjective judgments of disassembly task difficulty. The primary objective of the research is to reduce the subjectivity inherent in the evaluation procedure. A catalog of quantitative difficulty ratings for common disassembly tasks is generated. The scores are derived from work measurement analyses of the tasks and are based published motion-time data. The scores provide an analytical means for comparing disassembly tasks. The catalog is adapted to the previously developed ease-of-disassembly evaluation method. The evaluation procedure involves disassembling a product (or visualizing the process for conceptual designs), choosing difficulty scores from the catalog for the tasks involved, and recording the data in a spreadsheet-like evaluation chart. Task definitions, guidelines, and examples are included in the catalog and aid the evaluator in selecting appropriate scores. The revised disassembly evaluation procedure is demonstrated for both a computer keyboard and CPU. It is concluded that the catalog reduces the subjectivity in assessing task difficulty and makes the method an effective tool for identifying and assessing disassembly difficulty.