A Generalized Model for Cost of Manufacturing – a Deviation-based Formulation

Realistic modeling of cost of manufacturing is essential both for estimating cost of a product and for optimizing alternate manufacturing strategies. Although there are many factors that affect cost of manufacturing, the single most important parameter for estimating the cost of manufacturing is tolerance (deviation from the nominal size). Since tolerance affects the manufacturing cost directly, in the past most cost formulations were constructed using some form of inverse power function of a single tolerance parameter. However, to meet stringent quality and functional requirements more parts are now being controlled with geometric tolerances on top of size tolerances. In these situations, it is very difficult to establish a single representative tolerance parameter that can be used for estimating cost of manufacturing. A more general formulation is needed to extend the cost functions to deviations of all features of a part and the mating relations between parts so that the total effect of the prescribed geometric tolerances could be captured. In this paper we review existing single parameter cost formulations and then present an extension of cost formulations to a generic deviation-based formulation. We also briefly discuss the constraints and advantages of extending the cost functions to such multidimensional formulations.