Extending the Palmer algorithm to solve group flexible flow-shop problems

In simple flow shop problems, each machine operation center includes just one machine. If at least one machine center includes more than one machine, the scheduling problem becomes a flexible flow-shop problem. Recently, group scheduling has also been proposed and discussed. In the group scheduling, each job belongs to a specific group and all the jobs are processed group by group. In this paper, we propose a heuristic algorithm to solve group flexible flow-shop problems with more than two machine centers, which have the same number of machines. It first determines the job sequencing in each group by combining both the LPT and the Palmer approaches to solve the flexible flow-shop problems of more than two machine centers. It then determines group sequence by the Palmer approach. Experiments are also made to compare the performance of the proposed algorithm with the optimal solutions based on the dynamic-programming technique.