Influence of the Standard Components Integration on the Tolerancing Activity

Nowadays, designers use more and more standard components in the design process of mechanical products (aeronautics and automobile industries, etc.). Numerous products are made, for the most part, with standard components. By standard components we understand screw, nut, washer, transmission by belt or gear, ball bearing, etc. With current CAD modellers, the geometrical description of the standard components is easily integrated in the product description by the way of the standard geometric exchange formats (dxf, STEP) or the native formats (CATIA, Pro-Engineer). In consequence, the geometric description of standard components comes close to perfection. Nevertheless, what is the added value for the product? In terms of visualization the advantage is important but in terms of functional description of the product, nothing is added. The answer is the use of product models which allow to describe both functional and geometrical description. By the use of this approach, we try to demonstrate how the integration of standard components influences the tolerancing schema of the product. The functional requirements induced by the integration of the standard components have to be transferred on the parts of the mechanism according the ISO geometric specifications. Moreover this approach allows to distinguish the geometric specifications linked with the standard components from the others specifications