The application of computerized production control systems in job shop environments

Job shops are the most perplexing and challenging of environments for computerized scheduling systems. Some vendors call them problematic and avoid them whenever possible. The development of a generic scheduling tool that can be widely installed has eluded the many vendors who have tried. Installations in job shops are still painfully slow and are heavily customized. The wide variety of types of industry and processes found in the job shop category explains part of the problem. However, there is an additional challenge facing a scheduling tool after it has been installed: will it be used and does it really help the scheduler do the task of scheduling? Is the tool used for rough planning in the next few days or is it really used for dispatching on the fly by the people sequencing work? Few studies have looked at these issues and vendors are not willing to share this information. Furthermore, few customers who have invested significantly in the purchase and installation of a scheduling tool perform an unbiased postmortem or will share the results. In this study, we will present two field studies where computer scheduling aids were considered and discuss the requirements that will support the scheduler in the daily dispatch task. We have found that while analytical and algorithmic aids have limited benefits to a typical job shop, the appropriate use of computer technology can address information overload, cue filtering, and assist the scheduler in problem solving. We describe seven steps of the job shop scheduling task and the implications of each.