Effects of priority rules for production scheduling on complex industrial systems

Abstract

This paper discusses the efficiency of priority rules for the flexible flow line scheduling problem. This production environment is characterized by multiple identical machines at each stage and the possibility of jobs skipping one or more stages. Sequence-dependent setup times, which can be anticipatory or non-anticipatory, are also considered. The objective of the problem was the makespan minimization (total time to complete the schedule). This study can be classified as “applied research” regarding the nature, “exploratory” about the objectives and “experimental” as to procedures, besides the “quantitative” approach. The statistics used to evaluate the priority rules’ performances were the percentage of success (in finding the best solution), relative deviation, standard deviation of relative deviation and CPU average time. The priority rules LPT3 and LPT5 reached the best performances, considering both the descending order of the workload in all stages, in other words, on the production system treated, it's more advantageous priorizing the jobs with the biggest workload.