A three dimensional tolerance transfer methodology

This paper presents the adaptation of tolerance transfer techniques to a model called TTRS for Technologically and Topologically Related Surfaces. According to this model, design and process plan specifications can both be represented as a succession of surface associations on a combined representation tree. This tree can be enriched by the addition of technological attributes such as dimensional and geometrical tolerances. This provides the basis of a proper framework for the computation of tolerance transfer. Rules are indeed established to simulate tolerance chains or stack up which are generated according to paths or loops on the TTRS tree. Sets of equations are therefore generated and solved for each of these loop.