Applying process capability analysis chart (PCAC) in measuring sewing machine quality

The purpose of this paper is to promote a case study on a professional manufacturer of sewing machine was studied in central Taiwan. The research will construct a process capability analysis chart (PCAC) to evaluate process capability for a multi-process produce based on Cpk. The PCAC method improvement a technique of Six Sigma was introduced in this research which has three phases. The first phase calculates the values which are Cpk in 6, 5, 4 and 3a when the process means shifts by 1.5a; and then to construct PCAC in 6, 5, 4 and 3a when the process means shifts by 1.5a in the second phase. Finally, the influential quality characteristics that need to be improved must be located by the PCAC method. This method will be used to measure the aforementioned arbour bearings of sewing machine. The measuring outcome follows that the quality level of orthogonal degree arrived 6a. Not only can the PCAC model evaluate process capability for a product which holds many quality characteristics, but it can judge the process of precision and accuracy soon according to the points of fall for managers.