Design for Assembly Line Performance: The Link Between DFA Metrics and Assembly Line Performance Metrics

Abstract

While Design for Assembly (DFA) has been a useful design tool, it is not explicitly linked to actual manufacturing line performance. The motivation for this research came from the desire to link DFA directly to line balance and cycle time performance. The natural question that arose was whether these issues could be considered at the design stage by using the metrics that are derived from a DFA analysis. It is known that the time required to assemble a product can be estimated from both a DFA analysis and from a manufacturing analysis. This work links these two analysis methods so that the manufacturing parameters can be estimated and used to guide the design of a product. Starting with a DFA analysis, the minimum number of workstations needed to balance the line that will maintain the production rate (takt time) and precedence constraints is determined. Then the precedence constraints are systematically relaxed in order to generate measures on a component-by-component basis as to the impact it could have on reducing cycle time and improving line balancing performance. These measures, coupled with an understanding of precedence types, are used to identify design improvements to a product. To illustrate how product designer can consider assembly line performance issues during the design stage of the product, the methodology has been applied to an ABS brake assembly.