A Machine Selection Rule for Dynamic Job Shop having Alternative Machines with Different Processing Times

Generally, a job shop consists of work-centers in which alternative machines with different processing efficiencies exist. This paper presents a machine selection rule used to select a machine to process an operation from the alternative machines in a work-center. For dynamic scheduling, the proposed rule takes into consideration not only minimizing the current workload of the bottleneck machine but also minimizing the total workload. Machine selection methods by delaying decision until a machine becomes idle are also examined and compared with the proposed rule. Numerical experiments show that the proposed rule is simple but effective and robust.