Order scheduling problems in make-to-order manufacturing systems

As customer requirements become various and individual, make-to-order (MTO) production is accepted by a lot of manufacturers. In a MTO company, how to fulfil customer orders on time is crucial. Determining when to deliver and what quantities to deliver is the "order scheduling (OS)" problem. Under the influence integrated by many factors, order scheduling becomes very complex. Ideally, order scheduling should be coupled with shop production scheduling (PS). In this paper, resource capacity, order priority and lead time are considered as the key factors affecting OS. Resource capacity problem is decomposed into material resource and machine resource subproblems, and bottlenecks of them are mainly discussed, including the influence on lead time. Then an integrated solution framework, regarding all of the factors above, is presented to help MTO manufactory to decide a proper order scheduling. Virtual manufacturing (VM) technology and heuristic arithmetic theory are used in this paper, and a simple but practical queuing model is explored to help solving the order scheduling problems in MTO manufacturing systems. Data from a manufactory producing belt pulleys is used to illustrate the application of the model.