Tolerance control and propagation for the product assembly modeller

With the increasing use of computer-aided design (CAD) packages and modellers in engineering have come reduced product lead times and the incorporation of design for manufacturing (DFM) principles leading to concurrent engineering. Until recently, however, most CAD packages have been mainly concerned with accurate design representations in terms of nominal specifications, and the representation of tolerances on these systems in a manner that could be interpreted and used constructively in DFM and other manufacturability analyses have been ignored. This research develops a Tolerance Control and Propagation (TCP) engine for PAM, a product assembly modeller developed by the Automation and Robotics Laboratory. Tolerance control ensures that given individual dimensions, their tolerances and distributions, the designer specified functional dimension tolerance can be met with a specified level of confidence. Tolerance control is performed using Monte-Carlo simulation and the assumption of a beta distributed sum ...