ECONOMIC SCHEDULING OF A NEW ORDER IN A JOB-SHOP PRODUCTION SYSTEM

Generally, processing a new order in a job-shop production system affe cts the schedule of other products. This change of schedule of other p roducts results in some costs such as set-up cost, inventory cost, re- schedule cost. The amount of these costs depends upon the schedule (pr ocess starting time) of the new order for processing in a predetermine d schedule of multiple products in a job-shop. The application of queu ing theory for determining the optimal scheduling of a new order in a job-shop manufacturing system is discussed. The basic criterion consid ered for the new order scheduling/process starting date is the minimiz ation of total variable cost. The total variable cost consists of the cost elements: (i) raw material waiting cost or unavoidable waiting ti me for the new order; (ii) inventory carrying cost for the new order d ue to early completion or penalty cost due to late completion or deliv ery; (iii) re-schedule cost due to change in schedule of the other ite ms. An example is given to illustrate the application of the model.