Sess. 4-2 Proposal of the new process capability index (Cph) to the single-sided specification by using only half of sample size at non-normal distribution

Abstract

In some of our products, certain measurement data may not show normal distribution. We wanted to propose a new index, similar to Cpk, to reflect the process capacity correctly, even for the data distribution not having normal distribution, e.g. asymmetrical distribution. If only data smaller than MEDIAN is taken into account then the distribution sets close to normal distribution. By using this method, Cpk showed the analogous value to actual process capability, thus this method was proved to be effective.