A general formulation is derived, detailed modeling and analysis procedures are outlined, and the method is applied to two example problems. Tolerance analysis of assemblies promotes concurrent engineering by bringing engineering requirements and manufacturing capabilities together in a common model. By further integrating the engineering modeling and analysis with a CAD system, a practical tool for product and process development is created. It provides a quantitative design tool for predicting the effects of manufacturing variation on performance and cost in a computer-based design environment. The method is consistent with engineering design practice and is well suited for integration with commercial CAD systems.
Dimensional variations account for small changes in size due to manufacturing processes.
Geometric variations describe changes in shape, location and orientation of features. Kinematic variations describe the propagation of variation through an assembly by small adjustments between mating parts. Design intent is expressed by assembly tolerance specifications, which may be added to the model and used in computing predicted quality levels. A basic set of assembly tolerances is described, patterned after ANSI Y14.5 geometric feature controls, for specifying design requirements for a wide variety of applications. A complete computer-aided tolerancing system is described, which is tightly integrated with a commercial CAD system.