There are a number of articles on the flexible flowshop scheduling problem with the objective of minimizing makespan available in the literature. However, only a few articles have addressed this problem involving due dates. Therefore, research involving due dates in production environments has become extremely important due to the increasing competition and rising demand. This paper analyses the total tardiness minimization in flexible flowshops. Two new dispatching rules, based on the well known MDD rule and PRTT, are proposed and evaluated in 4.320 sets of instances. The second rule considers not only the jobs available at each scheduling moment, but also all jobs that have not been scheduled yet. Comparative tests with well known dispatching rules show that those rules outperformed the best rules known for the problem considered.
Flexible flowshop; Tardiness; Heuristic
