تعیین اندازه دسته تولید بهینه با سیستم تولید غیر قابل اعتماد

The classical lot sizing model deals with economic lot sizing for production in a deterministic framework. In real life, various forms of uncertainty affect the production. These include machine breakdown, quality variations, and so on. This paper develops a model with unreliable production systems and under alternative repair option strategies.

In a batch production system, items are produced in lots. Economic manufacturing quantity (EMQ) deals with the determination of the optimal lot size to minimize the total cost per item produced. The classical EMQ model assumes a deterministic framework where demand per unit time is assumed to be constant, the setup and holding costs do not depend on the lot size and the process produces items at a constant rate. The optimal lot size to minimize the total cost (comprising setup and holding costs) can be found in [1,2]. In reality, there are many types of uncertainty which affect the production process and this in turn impacts on the economic lot size. Quality variations and unreliable production systems are two such uncertainties. A review of the literature in EMQ with these types of uncertainties is given in Section 2. This paper deals with a new model for EMQ with unreliable production systems. When the production system breaks down, one has the option of either terminating the lot or continuing with the lot production after repair. Two types of repair are considered. The paper examines a combined repair and termination strategy and lot sizing to minimize the asymptotic cost per item produced. Section 3 gives the details of the model formulation. In Section 4, the analysis of the model is carried out and, in Section 5, a numerical example is presented. We conclude with a brief discussion of some topics for future research in Section 6.