STATISTICAL TOLERANCE SYNTHESIS USING DISTRIBUTION FUNCTION ZONES

{Tolerance is one of the most important parameters in design and manufacturing.Tolerance synthesis has a signi® cant impact on manufacturing cost and productquality. In the international standards community two approaches for statisticaltolerancing of mechanical parts arebeingdiscussed: processcapabilityindicesanddistribution function zone. The distribution function zone (DFZone) approachde® nesthe acceptability of a populationof partsby requiringthat thedistributionfunction of relevant values of the parts be bounded by a pair of speci® ed distri-bution functions. In order to apply this approach to statistical tolerancing, oneneeds a method to decompose the assembly level tolerance speci® cation to obtaintolerance parameters for each component in conjunction with a correspondingtolerance-cost model. This paper introduces an optimization-based statistical tol-erance synthesis model based on the DFZone tolerance speci® cations. A newtolerance-cost model is proposed and the model is illustrated with an assemblyexample.