Concurrent Dimensional and Geometrical Tolerance Balancing

An optimal design method for dimensional and geometrical tolerances (DGTs) has been presented and validated. In concurrent design environment, this method can directly allocate required functional assembly DGTs into pertinent process DGTs by using the given process planning of related components. The geometrical tolerances are treated as equivalent bilateral dimensional tolerances or additional tolerance constraints according to their different functional roles and engineering semantics in manufacturing. After the process sequences of related workpieces have been determined, concurrent tolerance chins, which express the relations between assembly DGTs and related component DGTs, are formulated by application of integrated tolerance charts. Concurrent tolerancing has been implemented through a linear programming approach, which simultaneously optimizes process tolerance based on process accuracy constraints. In optimization model, the objective is to maximize total weight process DGTs. Weight factor is used to evaluate the different manufacturing costs between different means of manufacturing corresponding to the same tolerance value. Economical tolerance bounds of related operations are formulated as constraints. Finally, an example is included to demonstrate the proposed method