The functional build approach to tolerance development

This paper describes a new paradigm, known as “functional build”, for finalizing design specifications on manufactured components prior to the start of regular production. Under functional build, manufacturers use a preproduction assembly to evaluate whether components build dimensionally correct assembled products, even if some individual component characteristics do not meet their original specifications. If the components form a functionally acceptable assembly, manufacturers then adjust component design specifications based on the dimensional data of the physical parts. Although a functional build tolerance adjustment strategy is applicable to any assembly, it appears most useful for those containing nonrigid components such as a car body where the sheet metal components can change shape or deform during assembly. This paper examines the advantages of using a functional build strategy over the traditional approach to tolerance adjustment during process validation