The Limits of Japanese Production Systems

Zangwill [Zangwill, W. I. 1992. The limits of Japanese production theory. Interfaces22(5) 14–25.] claims that reductions in setup coat and time can paradoxically increase inventory levels and holding costs without bound and, thereby, blow up total costs. One limitation of this claim is that inventory does not grow without bound for a system with more than one item. Inventory increases conditionally. I offer such a condition. Use of this condition can ensure, wherever possible, that setup time reductions do not back-fire through longer waiting times and higher inventory levels.