Combining tolerance design and monitoring process capability in a design-manufacturing integration procedure

Abstract

Traditionally, tolerance design and process capability control for new product development belong to the design and manufacturing stages respectively. In fact, they determine the finished product's cost, function, and quality, and should be considered concurrently. This paper provides a design—manufacturing integration procedure to enhance the efficiency of new product development. The procedure includes a total cost analysis, process capability indices, and an altered Ix - Iy monitoring chart. In particular, the process capability indices are considered in the total cost function in order to establish the relationship between quality variability and tolerance design. The use of this procedure should help designers to determine the optimum tolerance when considering not only the total cost but also the level of process capability that a manufacturer can supply. Similarly, it also can help manufacturers to simply and accurately indicate the status of their production in meeting the required tolerance levels. Finally, the proposed procedure is applied to an assembly study to illustrate how the proposed procedure can be employed in practice.