Fuzzy Design of Process Tolerances to Maximise Process Capability

A novel formulation for designing process tolerances to maximise the process capability index is presented in this study. The proposed model simultaneously optimises the process capability of each operation, and is consolidated into a single objective fuzzy programming. A step fuzzy membership function is employed to represent the lower and upper bounds of the process capability index, the problem is then solved by finding the maximum value of the fuzzy number. This study is believed to be the first attempt to design process tolerance with the maximisation of process capability index. A comparison of the results shows that the fuzzy model is suitable for assigning tolerances to an existing process.