Process Tolerancing: A New Approach to Better Integrate the Truth of the Processes in Tolerance Analysis and Synthesis

Limits of traditional Tolerancing methods are demonstrated for long. Worst-Case is so pessimistic and requires a 100% checking, providing scrap for nothing. Statistical Tolerancing RSS becomes risky when idealized centering assumptions are not perfectly achieved. New reliable methods exist, allowing to achieve the Capability requirement on resulting criteria, by using “population specifications” from ISO 18391.One is “Inertial Tolerancing”, from Pillet. We propose an alternative named “Process Tolerancing”, improving Semi-Quadratic methods fromMansoor, Greenwood or Taylor, and better adapted to industries of not daily adjustable toolings. This paper compares these 2 methods and illustrates their differences.