OPTIMAL PROCESS SEQUENCE IDENTIFICATION AND OPTIMAL PROCESS TOLERANCE ASSIGNMENT IN COMPUTER-AIDED PROCESS PLANNING

An approach for generating the optimal process tolerances and for evaluating alternative process sequences in process planning is presented. The formulations for evaluating production costs of a process sequence and its production operations are established. Several new production cost-tolerance models for production operations, which can significantly improve the modelling accuracy of empirical data of typical production processes, are introduced. Constrained nonlinear optimization is applied to identify the optimal process sequence and to determine the optimal process tolerances with least production costs. The method can improve present CAPP methods by introducing quantitative analysis. It can be combined with the knowledge-based generative CAPP approach to automatically generate the optimal sequence of production operations and the optimal process tolerances for a given design feature. An example is used to illustrate the method.