SIMULATION MODELING OF A MANUFACTURING ENTERPRISE WITH COMPLEX MATERIAL, INFORMATION AND CONTROL FLOWS

This paper describes practical problems encountered in modelling and simulating complex system interactions in a manufacturing enterprise. In addition to production, the interactions of diverse activities such as sales forecasting, order processing, production planning, material requirements planning, material procurement and distribution are considered. The preliminary results of such modelling and simulation are described. A graphical model of the order-to-ship (OTS) process, which consists of the activities that occur between the receipt of orders and the shipment of products within a factory, was built using hierarchical process modelling (HPM), derived from IDEF-0. Simulation model components for the OTS process were built using object-oriented programming and discrete-event simulation concepts. These reusable components were implemented in the class structure of the common Lisp object system (CLOS) within a manufacturing enterprise simulator (MES), on which different manufacturing enterprise models (MEMs), including the OTS model, could be executed. Simulating factory operations with the OTS model to generate system performance measures such as order backlog and finished goods inventory provided preliminary results on why customers experience delivery delays when the manufacturing enterprise has plenty of finished goods on hand.