Dynamic batch scheduling in a continuous cycle-constrained production system

In this work we address the problem of batch sizing and sequencing in a continuous metal sheets painting line with the aim to minimise set-up costs and maximise certain production parameters like work in process and throughput. In such production systems a set-up activity is needed when the painting colour has to be changed; colour requirements can be different for metal sheets produced in the same or in different batches, or when production line is discontinued for a certain time period due to over capacity, roster changing or maintenance activities. Starting from the Wagner–Whitin model, a new heuristic approach is presented with the objective to minimise the number of set-ups to be made for each lot. The heuristic approach has been validated through a discrete events simulation, in which the main production parameter is monitored to verify the effective improvements.