Material Requirements Planning[物料需求计划](PPT-33).ppt

Material Requirements Planning (MRP) Requirements for Effective Use of Dependent Demand Inventory Models Effective use of dependent demand inventory models requires that the operations manager know the: master production schedule specifications or bills-of-material inventory availability purchase orders outstanding lead times The Planning Process Bill-of-Material List of components quantities needed to make product Provides product structure (tree) Parents: Items above given level Children: Items below given level Shows low-level coding Lowest level in structure item occurs Top level is 0; next level is 1 etc. Bill-of-Material Product Structure Tree Material Requirements Planning (MRP) Manufacturing computer information system Determines quantity timing of dependent demand items Structure of the MRP System MRP and The Production Planning Process Master Production Schedule Shows items to be produced End item, customer order, module Derived from aggregate plan Derivation of Master Schedule MRP Dynamics Supports “replanning” Problem with system “nervousness” “Time fence” - allows a segment of the master schedule to be designated as “not to be rescheduled” “Pegging” - tracing upward in the bill-of-materials from the component to the parent item That a manager can react to changes, doesn’t mean he/she should MRP and JIT MRP - a planning and scheduling technique with fixed lead times JIT - a way to move material expeditiously Integrating the two: Small bucket approach and back flushing Balanced flow approach Lot-Sizing Techniques Lot-for-lot - Order exactly what is needed. Economic Order Quantity - One order quantity. Part Period Balancing - Allow the order quantity to vary. EOQ ModelHow Much to Order? EOQ Model Equations EOQ ModelWhen To Order Extensions of MRP Closed loop MRP - Feedback to Capacity plan, MPS Capacity planning - load reports - Reported resource requirement in a work center. MRP II - Material Resource Planning - Considers other r