A Concurrent Engineering Approach to Design for Assembly

DFA (Design for Assembly) is important in that it potentially can reduce the estimated 15-70% of manufacturing cost that is attributable to assembly. Besides the reduction in cost, DFA promises additional benefits in increased quality, increased reliability, and shorter manufacturing time. While there has been considerable interest in DFA, the research that has been reported in this area tends to suffer from a considerable handicap, namely that the work reported focuses primarily on DFA, without taking the other Concurrent Engi neering (CE) aspects associated with the product fully into account. Therefore it is quite possible, for example, to use DFA approaches to redesign a product so that it is a good design from the perspective of assembly but where the redesign is difficult, time consuming or expensive to manufacture or test. Part of the difficulty in including perspectives, other than that of assembly, is the resulting complexity caused by the multitude of different considerations that have to be taken into account. This paper aims to address this problem by de veloping a methodology that models the different considerations as an abstracted network, called a CE-Nets. The CE-Nets, a variant of Petri Nets, only uses that information which is pertinent to DFA and therefore substantially reduces the problem of complexity. The basis of CE-Nets is described in the paper and an example is given. The CE-Nets approach offers three main potential advantages. First, it of fers the potential of including other CE perspectives in a DFA system, without undue complexity. Second, it is a graphical approach that allows users to examine the interaction between different considerations. Third, it applies a mathematical mechanism to the problem, with the potential of being relatively straightforward to computerize.