Integrating Design for Assembly and Design for Disassembly in Life Cycle Management for Developing a Sustainable Product Development Design Methodology

The extremely high and ever-increasing annual disposal rates of solid waste have caused a big problem for environmental protection in the world. Human society consumes resources, but it is not able to reproduce them. Human activities are still based on ??open cycles,'' starting from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific and technological research towards sustainability appears clear if it is based on this analysis: to find development systems based on ??closed cycles'' of resources. In order to achieve closed cycles during product design and development process, those stages that are related to sustainability need a new methodology. Between product development process stages, assembly and disassembly play key roles in supporting sustainability. Design for assembly is an approach to design the product in the way that has least number of parts and simplest assembly process with minimum cost required. And design for disassembly is an approach to find the best disassembly sequence with least time. But newly there are other approaches implemented in design for disassembly including approaches that influence sustainability. As a case in point enabling disassembly to support maintenance and part recycling is current research issue. There are different methodologies in design for assembly including design principles and rules, quantitative evaluation procedures, knowledge based approach, and computer aided design for assembly. On the contrary there are less developed procedures for design for disassembly. There are some quantitative and some knowledge based approaches developed for design for disassembly. In this paper, different methodologies in design for assembly and design for disassembly based on four case studies including a hair clipper, a speaker, an electric pot and a printer are studied and stages which are related to sustainability are highlighted. Next, regarding the relationship between those stages and cost analysis in product lifecycle management a new methodology that combines design for assembly and design for disassembly in product design stage is proposed. This methodology considers product recyclability in the early stage of design. Although this methodology may increase the assembly cost of some components, but totally leads to a better justification for product End of Life Value. This approach designs sustainable products which end to less disassembly cost and justifies the part recycling.