Generalized selective assembly

Abstract

Selective assembly has traditionally been used to achieve tight specifications on the clearance of two mating parts. However, its applicability is not limited to this particular type of assembly. This article develops a generalized version of selective assembly called GSA. It is a powerful tool that can be used to improve the quality of assemblies of single units of different component types. Two variants of GSA are considered: Direct Selective Assembly (DSA) and Fixed Bin Selective Assembly (FBSA). The former is selective assembly using information from measurements on component characteristics directly, whereas the latter is selective assembly of components sorted into bins. For each variant, the problem of matching the N components of each type to give N assemblies that minimize quality cost is formulated as a linear integer program. The component matching problem for DSA is an axial multi-index assignment problem, whereas for FBSA, it is an axial multi-index transportation problem. Simulations are performed to evaluate the performance of GSA and to find the optimal number of bins. Realistic examples are given to show that the proposed methods can significantly improve the quality of assemblies.