Stepwise Optimization for Model of Integrated Batch Production and Maintenance Scheduling for Single Item Processed on Flow Shop with Two Machines in JIT Environment

This paper elaborates an integrated model of batch production scheduling and maintenance scheduling on flow shop with two machines producing single item to be delivered at a common due date. The objective function of the model is to minimize total cost consisting of in process and completed part inventory costs, setup costs, preventive and corrective maintenance costs and rework cost on two machines. The Model was a mixed integer quadratic that contains some integer and binary variables, so that analytic search solution could not be used for the model. It was developed a stepwise optimization method to solve the model. This model describes the trade-off between production cost and maintenance cost as the increasing of production run length on two machines. An example is given to clarify how the model solved.