A Whale Optimization Algorithm based Solver for No-wait Flexible Flow Shop Scheduling Problems

No-wait Flexible Flow Shop Scheduling (NWFFSSP) is one class of scheduling problems found in production scheduling. An interesting characteristic of NWFFSSP is the requirement that jobs be processed continuously without a break from one particular stage to the next. Good production scheduling considers objectives such as minimizing the total production time (makespan) and the resulting CPU Time. In this paper, NWFFSSP is solved using the Whale Optimization Algorithm (WOA) metaheuristic algorithm to minimize two objectives, namely the total production time (makespan) and CPU Time. The experimental results conclude that makespan is inversely proportional to the population size and the number of iterations. In contrast, CPU time is directly proportional to the number of whales and iterations. Compared to the other three metaheuristics, namely Genetic Algorithm (GA), Simulated Annealing (SA), and Minimum Deviation Algorithm (MDA), WOA has the best performance in terms of makespan for small-sized problems. While in terms of time, although it does not outperform MDA, WOA is generally better than SA and GA.