Chiu‐Chi Wei, Yeong‐Hoang Lee and Ching‐Liang Chang
Proposes a new formulation for allocating process tolerances. The major contribution of the model is to assign tolerances with maximization of the conformance rate of the entire…
Abstract
Proposes a new formulation for allocating process tolerances. The major contribution of the model is to assign tolerances with maximization of the conformance rate of the entire process. The cumulative standard normal probability is used to estimate the scrap rate of each operation with respect to the machining accuracy of equipment, therefore, the design engineers are able to predict the failure rate before production. Results of comparison with other methods indicate that the proposed model can cost‐effectively assign tolerances.
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Ching‐Liang Chang, Chiu‐Chi Wei and Yeong‐Hoang Lee
Traditional failure mode and effects analysis (FMEA) determines the risk priority number by finding the multiplication of factor scores that are converted from the probability or…
Abstract
Traditional failure mode and effects analysis (FMEA) determines the risk priority number by finding the multiplication of factor scores that are converted from the probability or degree of problem occurrence without considering the relative importance of factors. This study applies fuzzy theory to eliminate the conversion debate by directly evaluating the linguistic assessment of factors, and uses grey theory to obtain risk priority number by assigning relative weighting coefficient without any utility function. Results of the illustrative example show that concurrent application of fuzzy method and grey theory can solve the problems that have arisen from conventional FMEA, and can efficiently discover the potential failure modes and effects. Indicates that, as a result, the stability of product and process can be assured.