Using production and transfer batches in flowshops under MRP control

This study investigates the impact of using material flow control and order release throttling mechanisms on shop floor effectiveness in MRP based order release environments. The research methodology involves simulation experiments conducted using a flow shop model of a manufacturing and assembly setting. Specifically addressed issue is the decoupling of shop floor control decisions from MRP release schedules. This decoupling effect is implemented through the use of smaller production batch sizes, staggering the release of the production quantities to initial work stations, and using transfer batches. In a 14 part/9 processes simulation environment, the effects of shop floor control decisions are evaluated based on average hours of work in process inventory and average number of tardy units for the simulated planning horizon. Experimental results suggest that increasing material flow frequency through smaller process and transfer batch sizes have significant consequences on inventory and service levels. By separating work in process inventories into two components, it is shown that reducing batch sizes may not affect inventory levels of asynchronized assembly units (i.e. component delay). The results also indicate the presence of a possible threshold effect for throttling and staggering work order releases where service levels are compromised and marginal gain on inventory reduction diminishes.