A case study of production scheduling in a chemical industry

The problem concerns the production of ‘woodstock’ plates in a workshop of a chemical industry; several, but not identical, machines may be used to process a set of jobs. A job is characterized by various parameters so that the efficiencies of the machines are different for a specific job. Change-over times exist to adopt a machine between two successive jobs. The main objective is to assign and schedule the jobs to minimize the makespan, but some due dates must eventually be taken into account. A mathematical formulation of the problem, using a dynamic programming approach, is first described; then a heuristic method is proposed and the results of a first implementation are presented and compared.