Tolerance representation scheme for a three-dimensional product in an object-oriented programming environment

A new tolerance representation scheme based on a hybrid CSG/B-Rep hierarchy is proposed. By using the object-oriented programming (OOP) concept, the specifications of each part, such as tolerances, functional requirements, cost functions, and machining processes, have been treated as classes with their own attributes. The inheritance, which serves as the major linking mechanism between databases in the OOP world, has been fully exploited to make the tolerance representation scheme efficient and robust. The representations of five types of tolerances (form, orientation, profile, runout, and location tolerance), as specified in ANSI Y14.5M - 1982, are discussed and presented. A prototype of the proposed tolerance representation scheme has been successfully implemented in the Wisdom's Concept Modeller.