Functional tolerancing and testing increase microassembly yield

Tolerance allocation is a critical issue in precision engineering and in microassembly. Generally, manufacturing components within the required tolerances is hard because of the high precision necessary to satisfy the product function. In this paper, a case study shows that tightening component tolerances doesn't always increase the yield. An efficient control strategy is a better approach to ensure the product functions and to increase the number of conforming products. The proposed control strategy is based on sampling tests to control the assembly process, and on a full batch test to guarantee the functions of the assembled product. The redesign of a micro product control strategy illustrates the interest of multiphysic functional tolerancing and testing in precision engineering.