Design improvement using process capability data

Historical process capability data (PCD) is commonly used during product design. Such data can be stored in a formal database known as a process capability database (PCDB). PCD is primarily used during product design to allocate tolerances or forecast and manage manufacturing variation. However using a PCDB for these purposes alone does not exploit its full potential. This paper describes a method by which PCD can be applied to predict product performance variation early in the design process, thus saving time and reducing subsequent redesign costs. More specifically it describes the use of PCD during the initial design stage to predict how the product will operate, in terms of functional reliability, after it has been manufactured. An illustrative example based on the design of an electrical connector is provided. In this case connector beam normal force is a strong indicator of connector reliability and the example shows how the variation of this normal force can be predicted during initial connector design.