Selection of machining datum and allocation of tolerance through tolerance charting technique

Abstract

Tolerance charting is an effective tool to determine the optimal allocation of working dimensions and working tolerances such that the blueprint dimensions and tolerances can be achieved to accomplish the cost objectives. The selection of machining datum and allocation of tolerances are critical in any machining process planning as they directly affect any setup methods/machine tools selection and machining time. This paper mainly focuses on the selection of optimum machining datums and machining tolerances simultaneously in process planning. A dynamic tolerance charting constraint scheme is developed and implemented in the optimization procedure. An optimization model is formulated for selecting machining datum and tolerances and implemented with an algorithm namely Elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II).The computational results indicate that the proposed methodology is capable and robust in finding the optimal machining datum set and tolerances.