A progressive approach for the integration of process planning and scheduling

Automated process planning has been recognized as an interface between computer-aideddesignand computer-aided manufacturing. To achieve true computer integrated manufacturing (Cllvl), 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 problemalone belongs to the classof nondeterministic polynomial complete (NP-complete) problemsand whencombined with processplanning, the resulting problemis evenmore 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 thispaper greatlyreduces the computational complexity of the integration problemand hence can be realized in a real manufacturing environment where time is critical.