Abstract
The simplest method for making a production schedule is dispatch of jobs to idle machine tools. The method has a tendency of making a compact and efficient schedule, however the completion time of a job is not determined till the job is selected as the next job on an idle machine. Then, online scheduling methods have been developed, in which the production schedule is made as a job arrives at a machine. In this paper, an online scheduling method is developed for flexible flow shops under the due-date related criteria. A special feature of the method is to set the target completion time for each job and each stage. By numerical experiments, it is clarified that the method is better than FIFO (First In First Out) rule and especially the performance of the online scheduling is greatly superior to FIFO for the shops with heavy workload.
