Trade-offs in cycle time management: hot lots

In manufacturing, higher priority is given to hot lots to reduce their cycle time. The impact of hot lots on the cycle time of other lots in the system is studied here. Object-oriented simulation experiments of a wafer fabrication model were run to investigate the above impact. The simulation results showed that as the proportion of hot lots in the work-in progress increases, both the average cycle time and the corresponding standard deviation for all other lots increase dramatically. Thus, it is argued that hot lots induce either a deterioration in service level for regular lots or an increase in inventory costs. Sound management accounting would require that these costs be estimated, possibly using an approach outlined here.>