مطالعه ای از مدل شبیه سازی پیشرفته برای باز سازی سیستم زنجیره تامین TOC تحت شرایط ظرفیت محدودیت

The Theory of Constraints-supply chain replenishment system (TOC-SCRS) is a replenishment method of the TOC supply chain solution and now being implemented by a growing number of companies. The performance reported by the implemented companies includes reduction of inventory level, lead-time and transportation costs and increasing forecast accuracy and customer service levels. However, when the TOC-SCRS is applied in a plant or a central warehouse, the determination of reliable replenishment time will encounter a conflict with the replenishment quantity, especially under the constraint of limited factory capacity. An enhanced simulation replenishment model for TOC-SCRS under capacity constraint is then developed. A numeric example and a sensitivity analysis are utilized to evaluate the application of the proposed model. Employing this proposed methodology will facilitate a plant or a central warehouse to successfully implement an effective TOC-SCRS.

A supply chain is a set of nodes which consist of production plants (PP), central warehouse (CW), regional warehouses (RW) and points of sales (POS), as shown as Fig. 1. The chain links supplies and customers, beginning with the production of products by a supplier, and ending with the consumption of a product by the customer (Beamon, 1998). The need for regional warehouse stems from the need to supply the market very quickly. In the business market of flaming competition in recent years, companies are plagued by the fluctuations in demand and inevitably present inventory management challenges of the right inventory in the right place (node) at the right time. An effective inventory replenishment method employed in the supply chain is one of the key factors to achieving low inventory while maintaining high customer delivery performance.

When the TOC-SCRS is applied in a plant or a central warehouse, the determination of RRT (i.e., replenishment frequency and replenishment lea time) will encounter a conflict with the replenishment quantity. That is because the replenishment frequency depends on the set up frequency in the plant and the replenishment lead time depends on the production lead time. As we know, however, the set up frequency and the replenishment lead time in the plant depend on the production quantity (i.e., replenishment quantity). It means that the replenishment frequency and the replenishment lead time must depend on the known replenishment quantity, especially under the constraint of limited plant capacity. However, in TOC-SCRS, the replenishment quantity is determined by the known parameters of the replenishment frequency and the replenishment lead time. Therefore, this is a big conflict and an issue to apply the TOC-SCRS in a plant or a central warehouse. An enhanced replenishment model for TOC-SCRS under capacity constraint is required to be provided to solve this conflict. In this paper, the concept and method of TOC-SCRS was first reviewed. The model of TOC-SCRS was then modeled and its feasibility of application in central warehouse was discussed. An enhanced replenishment model for TOC-SCRS under capacity constraint was then developed. A numeric example and a sensitivity analysis were utilized to evaluate the application of the proposed method. Employing this proposed methodology will facilitate manufacturing plants or central warehouses to successfully implement an effective TOC-SCRS.