Conditions for the successful implementation of finite capacity/MRPII hybrid control systems

Abstract

Manufacturing resource planning II (MRPII) is the most widely employed methodology for production planning and control. Many authors, however, have stated that the fundamental basis of MRPII is flawed: that is to say, scheduling is based on fixed manufacturing lead times/lot sizes with infinite capacity. There has also been great interest in alternative methodologies such as optimized production technology (OPT) which plans to finite capacity. As a result, there are now several software houses who offer finite capacity scheduling (FCS) tools designed to operate alongside MRPII packages. These provide detailed finite capacity planning while retaining the database infrastructure of MRPII. Such hybrids claim to give the benefits of FCS to established MRPII users without the need for re-implementation. This paper describes the operation of such hybrids. Based on a case study drawn from the automotive components industry, it discusses the pitfalls that might be experienced without careful consideration of planning methods in relation to Bill of Material (BOM) structures. In particular, it shows that for a hybrid to be successful, it is necessary to consider the system as a whole, rather than considering FCS as a simple addition to MRPII.