SIMULATION TESTS OF FCFS AND SPT SEQUENCING IN KANBAN SYSTEMS

One of the basic tenets of scheduling theory is that the SPT sequencing rule maximizes average production rates and minimizes average in-process inventories. This paper shows that on single-card kanban-controlled lines FCFS often has greater average production rates than SPT. Further, the performance of SPT declines relative to FCFS for larger queue capacities and less frequent material handling. Results for the single-card system are also compared to those of Berkley and Kiran [1]. In that article it was shown that for two-card systems with periodic material handling, SPT has larger average inventories than FCFS. This paper shows that these surprising results can be attributed to Berkley and Kiran's material-handling mechanism.