STUDY ON PRODUCTION LOT-SIZING IN MRP SYSTEM (1ST REPORT, SINGLE-ITEM, UNCAPACITATED LOT-SIZING).

This paper considers a single-item, uncapacitated lot-sizing problem in MRP system, and new heuristic approaches, called Forward-Forward (FF) method and Forward-Backward (FB) method are proposed. These methods are based on Silver-Meal (SM) method. For the initial production plan obtained by SM method, a cost minimum procedure for successive two lot-sizing periods is repeated forward from the first period or backward from the last period, which results the decrease of total cost for whole planning horizon. And to evaluate the performance of FF and FB methods, four heuristic approaches (FF, FB, SM, Part-Period-Balancing) are compared in fixed horizon and rolling horizon environments. By testing each method for various coefficiences of cost (set-up, holding) and demand variance, the cost deviation from the minimum cost by Wagner-Whitin (WW) method is analyzed. The result has shown that FF, FB methods may outperform the other heuristics and even WW method for rolling horizon.