2000 Volume 51 Issue 2 Pages 124-131
Suppose that a job-shop production system consists of a sales center with order-selection and a production center with switch-over. These main models are of periodic and semi-dynamic types. This paper discusses the problem of setting the leadtime of the two models and gives a scientific basis for economic leadtime. For this purpose, we apply the 2-stage design method to the two models. By the 2-stage design method, the economic traffic that maximizes the net reward (=reward-cost) is decided at the first stage. At the second stage, the economic leadtime is set under the economic traffic. First, the respective mean leadtimes are given by the corresponding stochastic models. The mean leadtimes are then obtained from the total mean holding time divided by the number of mean processing units. Next, the respective behaviors of net rewards and leadtimes are numerically considered under the four traffic variables, two selection criteria and two control levels. The existence of economic leadtime is ascertained here. Finally, a comparison of periodic and semidynamic types is given, and a sensitivity analysis of leadtime is shown. Generally, the semi-dynamic type is superior to the periodic type in terms of the economic leadtime.
