The purpose of dimensioning and tolerancing for process planning is to determine the dimensions and tolerances that are to be produced at each stage in the manufacture of a component in order that the design dimensions and tolerances specified on the engineering drawing of the component are satisfied. Three proposed objective functions for cost minimization are developed in this paper according to various situations. When cost information is available average cost per acceptable unit produced is minimized, otherwise ratio of number of components to be machined to output is minimized. If residual tolerances exist sum of manufactured tolerances are maximized by assigning weights according to their process capabilities. Combining these objective functions a computerized optimization program has been developed which determines the optimum set of dimensions and tolerances which satisfies the specified design dimensions and tolerances and the permissible machining allowances, with the cost of producing all dimensions to the respective tolerances to be minimal. This system takes into account machining cost, scrap and where in the production process it occurs, manufactured dimensions and their distributions, allocated tolerances and process capabilities.
