SCHEDULING SEQUENCE-DEPENDENT COLOUR PRINTING JOBS

A scheduling problem in the colour printing industry is considered in this paper. The problem is to find an optimal assignment of print jobs to each of a set of colour printers, as well as an optimal processing sequence for the set of jobs assigned to each printer. The objective is to minimise the makespan of the schedule to achieve a suitable balance between the workloads of the printers and the efficiencies of the job sequences assigned to the printers. A novel aspect of the problem is the way in which the printer set-up times associated with the jobs are job sequence-dependent — it is possible to exploit commonalities between the colours required for successive jobs on each machine. We solve this problem approximately by using a simple heuristic and three well-known metaheuristics. Besides colour printing, the scheduling problem considered here admits many other applications. Some of these alternative applications are also briefly described.