Minimizing job flow time for job oriented scheduling
 

Chung-Hsing Yeh*

School of Business Systems, Monash University, Clayton, Victoria 3800, Australia

Received 23 February 2001; accepted 4 August 2002

Abstract

This paper presents a multi-pass scheduling procedure for minimizing flow time of individual jobs scheduled by job oriented scheduling in a job shop environment. Forward finite loading and backward finite loading are applied between the operations of a job or between a set of assembled jobs to enable them to be scheduled as close to one another as possible, thus minimizing job flow time. Examples are given to illustrate the scheduling procedure for minimizing flow time of a job by forward or backward scheduling. Experiments conducted for examining the effectiveness of the procedure show that it significantly reduces the average flow time of the jobs for the problems tested. The more diversified of the jobs scheduled in terms of their routing sequence and operation attributes, the more effective the procedure.

Significance:  The finite loading technique of job oriented scheduling is used by most human schedulers in actual industrial settings. The multi-pass scheduling procedure for minimizing job flow time provides a structural approach to schedule improvement. It has practical advantages in shop floor control of individual jobs.

Keywords: Scheduling, Job oriented, Flow time, Finite loading, Job shop

* Corresponding author. Tel.: +61-3-9905-5808; fax: +61-3-9905-5159; email: chunghsing.yeh@infotech.monash.edu.au