ABSTRACT
As the name implies, queuing theory involves the study of queues or waiting lines. Unlike many other modeling methods, it is not process specific and can be used to model any dynamic system in which discrete events alter the state of the system. Queuing theory can be used to study any manufacturing or service system where a queue buildup occurs over time. Thus, the system can be an airport, a walk-in medical clinic, fast-food restaurants, or machine shop. In an airport, we see queue buildup occurring when departing airplanes wait for clearance from air traffic control to take off. Similarly, in a walk-in medical clinic, customers wait their turn for consultation with medical staff, and in a fast-food restaurant, customers wait to place an order and also to pick up their order. Jobs wait to be machined on an automated lathe in a machine shop. In this chapter, we will focus on the application of queuing theory to manufacturing environments. Queuing theory can be used to answer the following questions with respect to a given system:
• What is the expected number of parts waiting in a queue? • What is the expected time a part spends waiting in a queue? • What is the probability that a machine will be idle? • What is the probability of a queue being filled to capacity?
