Top-Down Decomposition of Multi-Product Requirements Onto Locator Tolerances

Abstract

The tolerance allocation problem consists of choosing tolerances on dimensions of a complex assembly so that they combine into an ‘optimal state’ while fulfilling certain requirements on an allowed variation. This optimal state often coincides with the minimum manufacturing cost of the product. Sometimes it is balanced with an artificial cost that the deviation from target induces on the quality of the product. This paper suggests a multiobjective formulation of the tolerance allocation problem to automatically decompose requirements for an allowed variation on a set of critical product dimensions. This formulation is demonstrated using a rear lamp on a car with multiple requirements on allowed variation. In this case only the tolerances on locators that locates the lamp on the body are considered. The paper also reviews a selection of work that has been made on solving tolerance allocation problems.