Lead time prediction in unbalanced production systems

Whether job due dates are set internally or externally, it is critical for the shop floor controller to be able to accurately predict job lead times. Previous research has shown that utilizing information on the congestion le vels along a job's route is more valuable than overall shop congestion leve ls when predicting job lead times. While this information is easily attaine d in a simulation model, in industrial applications the task may be conside rably more difficult, especially when lot splitting is used to accelerate m aterial flow. We examine the effectiveness of three lead time estimation pr ocedures which utilize different shop information in bottleneck-constrained production systems where lot splitting is practiced under a variety of exp erimental conditions. The results indicate that accurate lead time estimate s can be obtained using information pertaining solely to the bottleneck wor k centre when the bottleneck is at an entry work centre. This offers operat ions managers a substantial ease in implementation over previously reported methods. The results also show that the operations managers interested in accurately estimating job lead times are well advised to take advantage of the excess capacity at non-bottleneck work centres by performing additional setups, and take measures that reduce bottleneck shiftiness.