Multiplant MRP

The purpose of this article is to enhance single-plant MRP systems for coping with multiplant situations in which: the plants are regarded as cost centers, there exist multisourced parts, and the transportation costs are significant. The multiplant MRP system should recognize that parts are produced in different plants, make offset calculations for in-transit lead times, and consider transportation costs when establishing production requirements and shipping routes for multisourced parts. The objective is, beginning with the corporate-determined master schedule for finished products, to communicate in one planning cycle time-phased planned order release schedules and shipping/delivery schedules to each manufacturing plant producing components for the finished products. The authors first present a simplified framework for the multiplant MRP system, where a transportation algorithm is incorporated into the MRP logic. Then they refine this simplified framework to handle more complex aspects of a multiplant network. These complexities include the treatment of requirements that are not shipped on time and the regeneration of new MRP schedules. The authors also observe that the solution to the transportation problem described above is affected by the lot-sizing rules employed. In addition, they discuss several important issues and decisions that confront a firm when implementing a multiplant MRP system.