Minimization of scrap and rework costs by process tolerances allocation

The design of process tolerances plays a vital role in process planning, which is to design a sequence of operations for converting raw materials into the desired shape. The conventional manual approach and previous mathematical models lack the capability of predicting the probabilites of scrap and rework, and the process capability of machinery was not taken into account. As a result, the tolerances allocated may not be achieved economically. This study proposes a cost-effective means for assigning process tolerances to minimize the cost incurred by scrap and rework. Comparison with other methods indicates that the proposed model is ideal for designing process tolerances.