Scheduling a permutation flow shop with family setups to minimise total tardiness

This paper presents several procedures for scheduling a permutation flow shop with family setups when the objective is to minimise total tardiness. These procedures are tested on several problem sets with varying numbers of families, jobs, and machines, three setup time distributions, and various levels of due date tightness and variability. The results show that variable greedy algorithms are effective when solving small problems, but a neighbourhood search procedure that includes searches with a neighbourhood defined by the sequence of batches of jobs belonging to the same setup family is more effective when solving large problems. Results are also presented, showing that significant reductions in total tardiness can be obtained if the time required to perform the family setups is reduced.