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Serial Agile Production Systems with Automation

Department of Industrial Engineering and Management Sciences, Northwestern University, Evanston, Illinois 60208
Department of Industrial Engineering and Management Sciences, Northwestern University, Evanston, Illinois 60208
Department of Industrial Engineering and Management Sciences, Northwestern University, Evanston, Illinois 60208
hopp{at}northwestern.edu
s-iravani{at}northwestern.edu
biying{at}iems.northwestern.edu

To gain insights into the design and control of manufacturing cells with automation, we study simple models of serial production systems where one flexible worker attends a set of automated stations. We (a) characterize the operational benefits of automation, (b) determine the most desirable placement of automation within a line, and (c) investigate how best to allocate labor dynamically in a line with manual and automatic equipment. We do this by first considering two-station Markov decision process models and then studying three-station simulations. Our results show that the capacity of production lines with automatic machines can be significantly lower than the rate of the bottleneck. We also show that automating a manual machine can have a dramatic effect on the average work-in-process (WIP) level, provided that labor is the system bottleneck. Once a machine becomes the bottleneck, the benefits from further automation are dramatically reduced. In general, we find that automation is more effective when placed toward the end of the line rather than toward the front. Finally, we show that automation level increases the priority workers should give to a station when selecting a work location.

Subject classifications: cross-trained workers; serial line; Markov decision process; automation; capacity.
History: Received August 2002; revision received October 2004; accepted October 2004.