Development of a Smaller-the-better Process Capability Analysis Model under a Sampling Inspection Plan

In practice, quality managers often employ sampling inspection to test and evaluate process performance or product quality instead of a 100% inspection, owing to cost and time considerations. Based on this factor, this article develops a smaller-the-better process capability analysis model (SBPCAM) to measure whether process capability of a product with multiple quality characteristics conforms to customer requirements, based on the process capability index (PCI) of smaller-the-better C_(pu) with the functions of the accuracy index (A) and the precision index (P). In the proposed method, a control chart with joint confidence blocks (JCB) is used to reduce sampling error and to improve the reliability of the point estimate of index C_(pu). A numerical example is provided to illustrate the feasibility and effectiveness of the proposed method.