Comparative evaluation of tolerance control chart models

A comparative evaluation of two widely used tolerance stack up models is ca rried out. Experimental metal cutting tests of resultant dimensions obtaine d under one and two fixturing set-ups are used to test the underlying assum ptions behind the Wade and Bourdet tolerance chart models. Resultant dimens ions obtained under a single fixturing set up are found to be highly correl ated and free of fixturing error; their treatment under the Wade model can thus lead to overly conservative tolerance allocation which may reject an o therwise feasible process plan. The results of the experimental evaluation lend support to the Bourdet deterministic treatment of such resultant dimen sions. However, the probabilistic approach proposed by Bourdet does not gua rantee a solution.