Capability evaluation for a product family composed of unilateral and multi-process quality characteristics

Abstract

Quality is a key indicator for customer’s satisfaction on a product or service. It is also one of the most important factors that a customer takes into account in making selection among competing products and services. Generally, a product is featured by many quality characteristics on performance. A product family is composed of numerous types of products. Customers are satisfied when all performance quality characteristics of an entire product meet the preset specification. Obviously, neither unilateral process capability nor multivariate process capability indices can fulfill the above requirements. Therefore, this study will propose a novel process capability index, which exhibits one-to-one mathematical relation with process yield. Meanwhile, the relationship between six-sigma quality level and capability index will be discussed. In addition, the study will also evaluate the quality of a multi-process product with numerous unilateral specifications. Furthermore, because of the difference in production volume for the products of every type, an index based on the weight of production volume of individual product will be developed so that the product quality of the entire product family can be evaluated.