MRP and MPS are industrial terms that stand for material requirement planning and master production schedule, and there are several key differences between them. MRP is used to determine how many materials to order, while MPS is used to determine when materials will be used to produce an end item.
Materials requirement planning is a technique for inventory planning and maintenance. It is used to decide how much material is needed to order to have the right inventory on hand to keep the production schedule operating at maximum efficiency. MRP uses the bill of material required to produce a product, along with knowledge of existing inventory and the master production schedule, to decide what materials to order.
The MRP list is used to produce the list of what was produced and how much of the materials in the production facility were used to produce the last run of product per the master production schedule. A material requirement planning list can be reviewed, either by computer or by an individual who is knowledgeable about the MPS, and then used to determine what must be ordered for inventory to complete the next production run without any material shortages or lost time due to ordering.
The master production schedule, on the other hand, is the actual list that shows the timing of the production schedule. It also shows how much each machine can produce and how many shifts are being utilized. By basing the MPS on the MRP lists, the operators of the equipment can be assured that they will have neither excess inventory after a production run nor insufficient materials to complete the run on time. The MRP and MPS, therefore, work together to ensure maximum efficiency.
One important difference between MRP and MPS is that a master production schedule operates through only one layer of the bill of materials for a product. This means that it does not take into account all of the bills of material needed to make a product, while the material requirement planning protocol will take all of the materials required to produce a product into account, including those across different or separate bills of material. By using the two different strategies together, a production facility can make itself more efficient and lean running than if it did not use MPS and MRP techniques.