A Statistical Approach to Process Planning

This paper presents a formal method for the process planning of machined components using a statistical methodology that can be used in design to determine the percent defective for feature-based tolerance specifications when used in conjunction with a process planning system or more specifically a process tolerance chart. The paper begins with an approach for process selection and then goes through an illustration of a tolerance specification for hole features under a location specification of Regardless of Feature size. Once a formal process plan has been developed, a probability model is used in conjunction with a process tolerance chart to determine the effects of feature size and location specification on percent defective and product cost. A discussion is presented and the model is expanded to include location specification under Maximum Material Condition and Least Material Condition.