Workload Control with continuous release

Workload Control (WLC) is a production planning and control concept which is suitable for the needs of make-to-order job shops. Release decisions based on the workload norms form the core of the concept. This paper develops continuous time WLC release variants and investigates their due date performance in a simulation study. The results indicate that - while lowering workload on the shop floor - the percentage of jobs tardy can be reduced significantly when the appropriate release approach is applied. However a detailed analysis also reveals that the reduction is realized at the cost of extreme delays for a small set of jobs with high processing time requirements. To explore the possibilities of overcoming this negative side effect, adaptations of the continuous release approaches are studied in successive experiments. The results suggest that the continuous release methods will need the help of e.g. output control to avoid the extreme delays.