Process capability-based tolerance design to minimise manufacturing loss

In this paper we propose a nonlinear programming model, composed of a cumulative standard normal probability function and manufacturing cost, to design process tolerances. The tolerances are standardised in conjunction with the process capability of the machinery to minimise the total manufacturing loss that occurs owing to non-conforming parts. The proposed model has been applied to a workpiece manufactured through ten operations and solved by GINO (General INteractive Optimizer). A comparison between the results obtained by the proposed model and other methods indicates that robust process tolerances can be obtained by the new formulation.