Abstract

z Abstract We consider manufacturing systems consisting of many machines and producing many types of parts. Each part-type requires processing for a specified length of time at each machine in a prescribed sequence of machines. Machines may require a set-up time when changing between part-types, and parts may incur a variable transportation delay when moving between machines. The goal is to dynamically schedule all the machines so that all the part-types are produced at the desired rates while maintaining bounded buffer sizes at all machines. In this paper we study the interaction of two types of feedbacks, one caused by "cycles " of material flow in non-acyclic manufacturing systems, and the other introduced by the employment of closed-loop scheduling algorithms. We examine the consequences of this interaction for the stability properties of the manufacturing system in terms of maintaining bounded buffer levels. First, we resolve a previously open problem by exhibiting the instability of all "clearing policies " for some non-acyclic manufacturing

Citations