Specification Limits, Capability Indices, and Process Centering in Assembly Manufacture

Abstract

The problems with using C_pk indices for components to control the capability of an assembly process are well known. Suppliers of components may, for example, actually decrease the yield of conforming product at assembly by raising their own C_pk's. We present formula relationships which link component capability indices (Cp, C_pm, C_pk) and specifications at the supplier level with capability indices and specifications at the assembly level. The minimum level of C_pk (representing a bound on yield) and the minimum C_pm (representing centering on target) at the assembly level are derived.

• Capability Indices
• Statistical Process Control

Additional information

Notes on contributors

Mahmut Parlar

Dr. Parlar is a Professor of Management Science.

George O. Wesolowsky

Dr. Wesolowsky is a Professor of Management Science. His email address is [email protected].