Maximizing Throughput: The Value of Dispatching Rules

Manufacturing is an important part of Canada's economy, representing 11% of its Gross Domestic Product (GDP) as of August 2014. Due to globalization, many Canadian manufacturing industries face new challenges and, to remain globally competitive, they need to become more efficient. Industry Partner A was seeking efficiency gains by implementing Operations Research (OR) methods in their job-shops, particularly for their production scheduling. A job-shop is a type of manufacturing process in which small batches of a variety of custom products are made. As in many production models, it has a number of machines or resources on which the production work is processed. In job-shop scheduling, each job consist of several operations, each completed using a specific machine or resource for a set amount of time. The flow diagram in Figure 1 illustrates a hypothetical example of a job-shop. Each job has a due date by which time the job is ideally completed. At each machine, there are queued jobs waiting to be processed and a dispatching rule is implemented as a scheduling method to determine which queued job should be ‘dispatched’ for processing.

 

Andrew Brown, a graduate student at the University of Waterloo, was asked by Industry Partner A1 to analyze various dispatching rules and propose a method that reduced the number of late jobs as part of his Masters dissertation under the supervision of Dr. Stan Dimitrov. Hossein Abouee-Mehrizi, an Assistant Professor, ensured the content of this case complemented his course on scheduling theory.

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