Mixed-model Assembly Line Problem with Consideration of Sequence and Conveyer Speed Simultaneously

Abstract

In this paper, the authors investigate a mixed-model assembly line problem with the intention of maximizing work efficiency. There are some objectives for various points, such as minimizing work removes congestion and line stop time. In the case of minimizing line stop time, a longer cycle time compresses the stop time and improves the evaluation value. However, it increases idle time and results in lower work efficiency. In other words, a short cycle time increases the line stop time, but there is a possibility to increase work efficiency. Many studies have reported job sequence with a fixed cycle time. An assembly line system achieves higher work efficiency if the cycle time of the system can be changed. This paper focuses on an assembly line system that is able to adjust the conveyer speed to change cycle time and requires restart time after a line stop. In order to consider remove work efficiency including idle time, line stop time and restart time, the objective function is set to minimize the makespan as the length of a schedule. The objective function value is the time when the last product is completed at the final work station. The solution of this problem consists of job sequence and conveyer speed. The authors propose some methods using remove simulated annealing. The effect of the proposed methods is shown and the influence of the problem conditions on the makespan is investigated.