Lower confidence bound for capability indices with one-sided tolerance processes and measurement errors

摘要

The families of process capability indices (C_p)~u(u, v) and (C_p)~l(u, v) provide measurements of process performance for one-sided processes. In this work we deal with the problem of gauge measurement errors effects on the performance of these indices. We show that using a lower confidence bound without taking these errors into account, severely underestimates the true capability. In order to improve the results, we suggest using an adjusted lower confidence bound, and we give a Maple program to obtain this bound. We finally present a real study on a polymer granulates manufacturing process to illustrate how to make use of our suggestion.