Tolerance analysis and synthesis across assemblies: state-of-the-art review

Abstract

Tolerance accumulation, as a result of over-specification or under-dimensioning by the designer, determines how easy a product is to assemble. The result is either impossibly tight fittings, or excessive clearance, which affect the final performance and quality of the assembly. This is particularly true of the compact assemblies encountered in microelectronics products, such as portable phones, pagers and disk drives. The effectiveness of the design evaluation stage may determine a company’s success in product launches, and its profitability. Every year millions of dollars are wasted on unnecessary changes in engineering drawings, reprogramming of assembly lines, and reworking or even scrapping of products. Tolerance analysis and tolerance synthesis are therefore indispensable tools for designers and process planners when they are evaluating the designed product. Tolerance analysis is used to determine the final assemblability of components with specified individual tolerances. Its inverse, tolerance synthesis, ensures the reasonable and economical distribution of assembly tolerances on each component, thus helping to optimize product cost, quality and—ultimately—function. This paper summarizes over 100 publications to provide a review of the current state of the art in such research, and to point the way towards possible future research.