Method and Apparatus for Managing Very Small Fraction of Nonconforming under Non-Normal Process

摘要

According to an embodiment of the present invention, provided is a method of managing a minimum failure rate in a non-normal distribution process. The method comprises the following steps of: selecting one or more samples for each process for products produced by a product production process to analyze non-normality of quality characteristic values; calculating a minimum failure rate value of the samples for each process by using a standard limit value of a predetermined product for a Burr distribution function obtained through the analysis of the non-normality; calculating a Burr_Zp distribution for a minimum failure rate management based on the calculated minimum failure rate value of the samples for each process, wherein the Burr_Zp distribution is estimated through a maximum likelihood estimation (MLE) technique and defined as a normal distribution defined through average and variance; and designing a Burr-Zp management chart including a management limit line and dotting by using the Burr_Zp distribution.