Disassembly complexity and recyclability analysis of new designs from CAD file data

Abstract

It is well known that most decisions that effect the end-of-life disposal and recycling of a product are made during the product design phase. The premise of a design for environment (DfE) approach is that product designers will evaluate and improve their designs from an environmental perspective. The authors' survey of designers indicates they are typically overburdened with product functionality and cost reduction objectives. This more or less eliminates any serious DfE analysis, particularly in small and medium sized companies. There is therefore a need for DfE tools that require minimal user input and hence can be run automatically in the shadow of the design process. At MERC, the authors are involved in the development of such a suite of tools, which evaluate several life-cycle analysis dimensions simultaneously. In this paper, they present DfD-Compact, a design tool that evaluates disassembly complexity and material recyclability. The only input data required by this tool is readily extracted from common CAD programs. Specifically, this data includes a part relationship tree, part weight and part material composition. All other data is stored in standardized libraries. The CAD file data does not typically include all the data required to make a detailed analysis. The authors have developed a procedure that is able to use this core data to estimate other product data and then combine this with the library data to generate a reliable DfD-Ratio. This ratio evaluates the product in three dimensions: (i) material separation and recyclability; (ii) unfastening difficulty; and (iii) disassembly accessibility. The DfD-Ratio is measured on an open-ended scale starting from zero, with zero indicating the worst case. The higher the ratio the better the design. This ratio can be used by the designer to compare design alternatives, improve the design, and/or meet minimum DfE objectives. The procedure is illustrated by an example.