Choosing optimal buffering strategies for dealing with uncertainty in MRP

Dealing with uncertainty in the material requirements plan (MRP) is important, because of its importance in meeting the requirements of the master production schedule (MPS). In MRP, there is a critical need to make the MPS predictable and consistent. In the early days of MRP, a philosophy of zero safety stock or safety time was rigorously advocated. It was thought to be more advantageous to eliminate the need for buffering by freezing the MPS and managing lead times to make these firm. However, it was soon recognized that it is extremely difficult, in practice, to eliminate all uncertainty that affects the MPS and its execution. Practitioners know that some level of buffering is necessary (or inevitable) given the vicissitudes of the market place, production system planning and control, and supplier performance. This article accepts these premises and proposes a model and procedures for dealing with the buffering problem and choosing optimal buffering strategies in MRP.