Research On Stochastic Inventory Control Policy Of Equipment Spare Parts For Mold Manufacturing

Mold manufacturing is typical mode of production-order type, have the characteristics of Capital-intensive, technology-intensive, single and small batch production, quality, cost and delivery are the three elements of the mold. Mold manufacturing process is complicated, high-tech, there is no high levels of mold if not have high-quality; high-precision processing equipment. There are two factors for companies must reserve spare parts, first of all, if the equipment shutdown, the loss is very large; secondly, due to the randomness of shutdown and uncertainty of the purchase, in order to reduce maintenance time, companies had to reserve part of the spare parts. If the spare parts inventory mismanagement, the result is often: on the one hand spare parts inventory remains high level, there are many long-term spare parts stay in the warehouse become sluggish materials, take up a lot of floating capital, and now technology is developing rapidly, accelerated equipment upgrades, the problem of sluggish spare parts always exist owing to the depreciation of equipment; hand after when equipment shutdown, related spare parts often no or not enough. Therfore, under the condition of maintain equipment operating normaly, it is a expected solved problem that how to balance the cost of stockholding and shortage for enterprise. Spare parts are indispensable factor of manufacturing systems, good spare parts management can not only guarantee the normal operation of the manufacturing system, but also can significantly reduce the occupation of floating capital for enterprise, thereby enhancing economic efficiency of enterprises.First, the demand model of spare parts was created. According to the traditional ABC classification, through the relationship between demand and troubles to establish the correspondence table, unified demand model of class B spares parts was builded by the theory of linear equations..Next, the inventory control model of spare parts was created. Use (s, S) inventory control policy which instantaneous replenishment, in view of some of the limitations of analytic algorithm, Markov chain was used to built the Markov model for inventory and shortage quantity of the spare parts and the state transition probability matrix is reducted. On this basis, while maintaining a certain provided service level, based on the minimum long run average total cost targets established optimal stochastic inventory control model of spare parts in a check period. Then, the adaptability of heuristic algorithm was proposed and validate. Heuristic algorithm is proposed to solve the model, in order to speed up the convergence of the optimal solution, heuristic search rules which can effectively narrowing the scope was proposed for the optimal solution. Respectively, a examples of small, medium and large mold manufacturing company was provided, algorithm have been come true and heuristic rules was achieved through MATLAB simulation, the suitability of the algorithm was verified, it show that the method can solves the problem of class B spare parts which in stochastic inventory control system preferably.Ultimately, by the ERP system of a large tire mold manufacturing enterprise, spare parts inventory control module was developed to provide auxiliary support for order management of spare parts.In summary, this paper had a certain amount of research on inventory control problem of Class B spare parts for mold manufacturing enterprises, include the establishment of the unified demand models and stochastic optimal inventory control model for spare parts, heuristic algorithms, heuristic search rules and the calculation formula of Markov chain state transition matrix was proposed, On this basis, algorithm was validated in mold manufacturing enterprises of different sizes, the effectiveness and adaptability of the algorithm had demonstrated and has a certain theoretical and practical value.