A study of three classes of sequencing rules in a simulated job shop

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Virginia Tech

The purpose of this investigation was to study three classes of sequencing rules in a simulated Job Shop. A computer program simulating the Job Shop was developed to provide an experimental base from which the behavior of the Shop could be observed. In the simulated Job Shop, three sequencing rules, one from each class, were tested. The sequencing rules used were First Come First Serve (FCFS), Shortest Processing Time (SPT), and Probability Sequencing (PS). Due date performance, number of jobs processed in a simulated interval, number of jobs late, mean lateness and in-process inventory level were the measures of performance used.

The results indicated that at low traffic density there was no appreciable difference among the measures of performance for the three sequencing rules. At high traffic density SPT had the lowest inventory level but its mean lateness was larger than That of FCFS even Though its number of jobs late was smaller. The performance of FCFS and SPT did not change with changes in allowed flow time but for PS the in-process inventory level increased with decreasing allowed flow time and The number of jobs processed decreased with decreasing allowed flow time.