Lead time reduction through cyclic scheduling in a job shop

This paper describes the development of a Lean scheduling system for job shop environments for improving flow. The authors introduce a cyclic scheduling system with fixed interval length and time slots, which can be represented by a 'production wheel' (as a variant of EPEI scheduling). An iterative procedure to design the production wheel is proposed. Using the MSSI heuristic method, the production orders have to be scheduled on the wheel of the first machine(s) in the production chain. This heuristic minimizes the number of set-ups and the total amount of changeover time within the scheduling interval. Due to the limited number of time slots on the production wheel, it is possible to keep the total Work-In-Process (WIP) under control and consequently, also the lead times. A case study in a manufacturing facility in Belgium shows that the introduction of this scheduling system can reduce the average lead time by over 40%. This paper also explains how the production wheel can serve as a visual management tool to monitor and control the process status and progress.