An interactive micro-computer software for general three machines flow shop sequencing problems

The order in which jobs pass through machines or work centres is a sequencing problem. The sequencing problems occur in flow shop as well as job shop production systems. In flow shop production systems, each job follows the same processing route whereas in the job shop production system, jobs flow across machines or work stations on many different routes. For optimizing the sequencing of such jobs, production planners may adopt different criteria such as makespan time, average completion time, due date performance, machine utilization and so forth. In the absence of given criteria, it is usual to accept the makespan time as the criteria and to attempt to minimize this. In a 2-machines flow shop, the jobs can be sequenced optimally for minimum total makespan time by using Johnson's algorithm 1]. Johnson's algorithm can also be used to find the optimal sequence for special three-machines flow shop problems satisfying certain conditions 1]. But for general three-machines sequencing problems, optimal sequence based on makespan time can be obtained by using a branch and bound solution procedure 1].

In this paper, the branch-and-bound procedure have been used to develop an interactive program in BASIC for finding the optimal job sequence for general three-machines flow shop problems. This program which is written for an IBM-PC or IBM-PC compatibles, also provides the time chart and the time chart drawing. Furthermore, it gives the results of the branching steps (i.e the partial sequences) in a tabular form.