PROCESS CAPABILITY INDICESFOR GEOMETRICAL PRODUCT SPECIFICATION - CASE STUDY OF PROCESS CAPABILITY INDEX WITH SKEWED DISTRIBUTIONOFGEOMETRICAL PRODUCT SPECIFICATION

Generally, the geometrical characteristics are calculated in a composed way, as the normal distribution cannot be assumed in many cases. Various methods have been proposed to determine how the process capability index should be calculated in such cases. In this paper, using the data from the machining process, several methods presented in the ISO 22614 series and those presented thus far in Japan are examined and compared. Additionally, this paper analyzes what methods should be used in a certain case depending on the purpose and the status of the process (start-up or improvement of the process, assurance of the post-process).