Design of product specifications for multi-characteristic inspection

A product often requires inspection on more than one characteristic. The traditional method determines inspection specifications for each characteristic independently. This practice ignores the interactions among characteristics in determining the disposition of an item, and prohibits tradeoffs among the quality of characteristics. In this paper, two multi-characteristic screening (complete inspection) models are proposed with different information processing requirements. In both models, screening specifications are jointly determined by considering all the economic and stochastic factors associated with the characteristics of interest. However, in Model 1, each characteristic has separate screening specifications and the inspection results of conformance (acceptance or rejections) of all the characteristics are used to determine the disposition of an item. In the second model, a joint screening rule based on an aggregation of characteristics is used to allow direct tradeoff among the quality of characteristics. To implement the second model, the exact measured values of all characteristics of an item have to be recorded and used for a decision on that item. These two models are formulated and the solution procedures are developed. A numerical study is used to compare the cost performance and other plan characteristics of the independently-determined single characteristic models and the two multi-characteristic models.