Process capability analysis using Monte Carlo simulation

Many process capability indices have been proposed to measure process performance and sometimes companies do not know which process capability index is more sensitive and suitable. One of the main points of process capability indices is how much they take into account process variability, departure of the process mean from the target value, and proportion of nonconformity (loss). In this paper, we first review Cp, Cpk, Cpm and Cpmk. Then we illustrate a comparison among process capability indices. In order to compare them appropriately, random data are generated by Monte Carlo simulation and besides the calculation of process capability indices, losses of process are calculated with Taguchi loss function. The results show that in point of view of departure of the process from the target value, these process capability indices are same and in point view of variability, Cpk are more sensitive.