A Quality-oriented Statistical Tolerance Model for Improving Fit Quality

Aimed at improving the manufacturing processes of mating parts with relatively lower cost, a new statistical tolerance (ST) model for improving fit quality is presented. On the basis of studies on process quality indices and fit quality indices, the quality-oriented statistical tolerancing is introduced, which provides an interface between fit quality expectation and the process parameter design of mating parts. The quality-oriented statistical tolerancing under information-based manufacturing condition is discussed. Compared with independent ST model, the innovative method can achieve a designated fit quality and minimum defective ratio by fully utilizing ST zone and the known information of manufacturing processes of the mating hole and shaft parts. Thus, production cost for mating parts can be reduced obviously.