Using the virtual cell concept for short-term production planning for flexible job shop manufacturing systems

Short-term production planning (STPP) problems in flexible job shop manufacturing systems (FJSMS), which consist of computerized numerically, controlled (CNC) machines and dedicated machines, are discussed here. Short-term production planning problems of FJSMS include part type selection, process selection, batch sizing and part family/machine group formation. A proposed STPP system for FJSMS is developed for cases where production contents are frequently changed thus resulting in the physical machine layout being not justified. It mainly adopts a restricted-period planning approach, using a virtual cell's concept for solving the STPP problem. The planning goal of STPP is to satisfy quantity and due date requirements as determined by MRP/CRP, with due consideration to the features of NC machines and dedicated machines.