A Designer Guided Tolerance Specification for Fit Assurance

摘要

Tolerance synthesis for fit and function has been a difficult task for designers since the inception of geometric tolerancing standards. Designers who learn the geometric meaning of tolerances have difficulty connecting the application needs to the geometric precision needs. For this reason, poor tolerancing practices are quite widespread in industry. Attempts to automate tolerance synthesis using mathematical approaches without the need to have the designer activity involved have not resulted in robust solutions. Ideally, designers should participate in the formulation of fit and function needs at the application level such that an automated system can translate the needs into the corresponding geometric tolerancing specifications. This paper makes an initial attempt at developing a language for fit assurance so design engineers can easily achieve their tolerancing objectives in the familiar environment of functional needs rather than the more difficult geometric precision needs. The approach is based on developing a fit and function vocabulary to easily express the needs, a procedure to bring uniformity to the practice, and a set of rules to convert such needs to suitable geometric tolerances. The whole procedure is demonstrated in the context of a pair of example problems.