Benefits of lot splitting in job-shop scheduling

As the lot-streaming concept has been used widely to reduce the makespan in a production system, most research has investigated the flow shop production systems; however, job-shop production systems have received much less attention, relatively. This study more thoroughly investigates the application of lot splitting in a job shop production system with setup times, which cannot be omitted. The objective investigated not only minimises the makespan but also minimises the total production cost, which includes the material handling cost, the setup cost and the inventory cost. A disjunctive graph is first used to describe the addressed scheduling problem, and an integer programming model is then constructed to obtain an optimal solution. In order to investigate the influence of the number of sublots and sublot sizes on a job-shop production system with regard to the corresponding objective considered, some experiments are conducted and results presented as well.