A tolerancing framework to support geometric specifications traceability

Because manufacturing tools do not provide perfect geometry, designers have to control the deviations of the manufactured part's geometry. Nevertheless, the greater the number of toleranced parts in an assembly increases the more expensive the final product is. Consequently, designers only have to tolerance the influent surfaces of the mechanism that meet the functional requirement. Moreover, the earlier the geometric conditions are expressed in the design process, the better they conform to the functional requirements. In this paper, a product model is presented that allows designers to describe geometric specifications at any stage of the design cycle. In contrast to current models that support the functional and structural descriptions of the product, the product model presented also includes a description of the geometry with defects. Our product model used in geometric tolerancing enhances the traceability of the geometric conditions through the numerous transfer activities from conceptual to detail design. The benefits of the product model presented are illustrated with a car brake calliper design.