HIERARCHICAL PRODUCTION PLANNING FOR COMPLEX MANUFACTURING SYSTEMS

A hierarchical approach to production planning for complex manufacturi ng systems is presented. A single facility comprising a number of work -centers that produce multiple part types is considered. The planning horizon includes a sequence of time periods, and the demand for all pa rt types is assumed known. The production planning problem consists of minimizing the holding costs for all part types, as well as the work- in-process and the backlogging costs for the end items. We present a t wo-level hierarchy that is based on aggregating parts to part families , work-centers to manufacturing cells and time periods to aggregate ti me periods. The solution at the aggregate level is imposed as a constr aint to the detailed level problems which are formulated for each manu facturing cell separately. This architecture uses a rolling horizon st rategy to perform the production management function. We have employed perturbation analysis techniques to adjust certain parameters of the optimization problems at the detailed level to reach a near-optimal de tailed production plan. Numerical results for several realistic exampl e problems are presented and the solutions obtained from the hierarchi cal and monolithic approaches are compared. The results indicate that the hierarchical approach offers major advantages in computational eff iciency, while the loss of optimality is acceptable. Copyright (C) 199 6 Elsevier Science Limited