Earliness/tardiness production planning by JIT philosophy for job-lot manufacturing systems

In this paper, we study the problem of production planning for the typical job-lot manufacturing system. The production in this kind of manufacturing system has such features as global-market-oriented, one-of-a-kind production, differentiating products with high manufacturing cost, complicated structure and long manufacturing cycle time. Just-in-time production and delivery is the key element to be considered. Here, an earliness/tardiness production planning approach is proposed. It is compatible with the concept of JIT production and extends study of the single machine earliness/tardiness (E/T) scheduling problem. An E/T production planning model is established which minimizes the earliness and tardiness penalties of all products under total production capacity constraint. The Lagrangian relaxation algorithm is developed to solve the model. To combine MRP-II with JIT philosophy, we have embedded the E/T planning approach into the master production scheduling (MPS) or MRP-II, and have designed a hierarchical master production scheduling system. The E/T production planning approach and the designed MPS system are successfully applied to the computer integrated manufacturing system (CIMS) of the Shenyang Blower Plant in China, a typical one-of-a-kind manufacturing plant. Satisfactory results are reported.