Decision Sciences Journal of Innovative Education Volume 7 Number 1 January 2009 Printed in the U.S.A. TEACHING BRIEF The Sandwich Factory: An In-Class Demonstration of Pull Production Concepts Timothy S. Vaughan † and Justin P. Gardner Department of Management and Marketing, University of Wisconsin – Eau Claire, Eau Claire, WI 54702-4004, e-mail: vaughats@uwec.edu, gardnejp@uwec.edu INTRODUCTION A number of in-class simulations have been presented that attempt to demonstrate the difference between push versus pull production systems. A typical scenario is a three- or four-stage sequential production process, producing a single product such as paper airplanes, Lego assemblies, and so on (see, e.g., Billington, 2004). During the initial runs, unbalanced activity times naturally result in some upstream station outproducing a downstream bottleneck. A kanban method is then introduced, with students instructed to produce only when downstream demand generates a signal authorizing production. This naturally forces all stations to keep pace with the bottleneck, eliminating work-in-process (WIP) build-up and decreasing throughput times. The mechanics of a pull system can certainly be demonstrated in this manner. Nonetheless, the student comes away with the impression that pull production is little more than a line pacing mechanism. Moreover, the implication seems to be that converting to pull would be a simple matter of deciding to “switch over” to an alternative approach. We have used a simple but compelling simulation of a production facility called the “Sandwich Factory.” The simulation not only demonstrates the mechan- ics of the pull system, but also demonstrates the critical role of process flexibility in enabling pull production. We should note that this exercise is conceptually distinct from that of Cox and Walker (2006), which uses poker chips to demonstrate mul- tiechelon supply chain dynamics, using round-by-round play in a manner similar to the Beer Game (Sterman, 1989). THE GAME Our fictitious producer makes a variety of different “sandwiches” using red, white, and blue poker chips. There are six product varieties, for example, the “BWB” (a single white chip sandwiched between two blue chips), as well as the “WBW,” “RWR,” “WRW,” “BRB,” and “RBR.” The player positions include a sandwich † Corresponding author. 259