A pragmatic approach to interactive assembly sequence evaluation

Abstract

An assembly-oriented design system has been developed which includes several analysis tools to improve product assemblability during product development. One of these tools supports the parallel development of the product design and the assembly sequence, thus exploiting the benefits of concurrent consideration of product and process. However, this approach requires some method for evaluating the sequence against requirements. Previous work on assembly sequence evaluation has concentrated on identifying the best from a set of ranked alternatives. When a single sequence is constructed, as with this tool, another method is needed. This paper reports the development of this novel methodology for evaluating individual assembly sequences. A review of the relevant literature has found several measures for identifying good assembly sequences from a ranked list and the fundamental sequence attributes extrapolated and aggregated. This leads to the proposal of four new indices: insertion index, stability index, difficulty index and complexity index. A large number of assembly sequences have been analysed to define limiting values for the indices such that they can quantify the potential of an incomplete sequence resulting in a satisfactory solution. The application of these indices in concurrent design and assembly planning is illustrated through an industrial case study.