A progressive approach for the integration of process planning and scheduling

Automated process planning has been recognized as an interface between computer-aided design and computer-aided manufacturing. To achieve true computer integrated manufacturing (CIM), process planning should be integrated with scheduling. One approach to this integration problem is to merge process planning and scheduling into a single optimization task. However, the scheduling problem alone belongs to the class of nondeterministic polynomial complete (NP-complete) problems and when combined with process planning, the resulting problem is even more difficult. One solution to this is to adopt a progressive approach, in which the interaction between process planning and scheduling starts from a more global level and ends at a more detailed level. The progressive approach described in this paper greatly reduces the computational complexity of the integration problem and hence can be realized in a real manufacturing environment where time is critical.