Dynamic flexible flow shop scheduling with theory of constraint and time window approach to minimize mean tardiness.

Center for Material and Technical Products (B4T) is a government agency under the auspices of the Indonesian Ministry of Industry. The problem faced by the B4T Automotive Laboratory is that the company's target in the tire testing process is not achieved because it is unable to achieve the target of increasing the capacity of 10% annually. This is due to the large number of tire testing orders that have been delayed from the specified due date. The flow pattern that occurs in the tire testing process is a flexible flow shop type. The current scheduling method used is the FCFS method which is considered less effective because it does not see the capacity of each machine, causing waiting time and bottlenecks. Another phenomenon that causes the opportunity for greater delays because dynamic job arrivals have not been accommodated, the schedule made must be able to keep up with job changes and rescheduling. This research focuses on improving and designing a rescheduling model that can accommodate dynamic job arrivals by combining the TOC and Time Window with the aim of minimizing the mean tardiness so that it can meet the predetermined due date. The proposed scheduling method uses a combination of the algorithm for determining the length of the time window with the branch and bound algorithms of Ignall and Scharge. Time window algorithm is used to accommodate dynamic job arrival patterns. Meanwhile, the branch and bound algorithm is used to find the optimal sequence of jobs scheduled in the flexible flow shop flow. Meanwhile, the scheduling method used to schedule jobs at non-constrained stations is to use backward scheduling because the constraint station is at the end of the process. The results of this proposed scheduling have better efficiency in reducing the average time for job delays by 31%. So that this proposed scheduling model can be recommended to be applied in the B4T Automotive Laboratory in overcoming the problem of job delays in the tire testing process. [ABSTRACT FROM AUTHOR]