Research On Work-in-Progress Control In Serial Production Logistics Systems

As the customer demand is diversified and the request for the improvement in timely product delivery is stronger, company must promote its response ability to meet the requirements of customers; meanwhile, it is getting increasingly important to maintain lower and steadier WIP in the whole value chain. WIP in Production Logistics Control Systems is a main bottleneck ,it is limit the respondence between external environment and enterprise, also, it is an obstacle for system target on efficiently use in resource, short processing cycle, low inventory and JIT. Therefore, in order to improve the production logistics system stability, as well as to meet the needs of enterprise competitiveness, it is necessary to effectively control the input and output in entire production system. This paper, based on the control theory, build a WIP control model under the PID controller in serial production line that overcomes the shortcomings of the traditional PLCS in dynamic environment, and provide the simulation analysis to the model.This paper refers to WIP in discrete serial production line. Firstly, in reviewing and summarizing the modeling method of the current production logistics system, and combined with the dynamic characteristics about the current manufacturing system and latest developments in control theory ,a WIP control model of integrating the feed-forward and feedback control loops in serial production lines is proposed, which analyzes three control strategies: the demand smoothness, the production delays and the inventory replenishment rules, of the model used a stable of demand, production delays, the restoration of the three inventory control strategy. Secondly, Based on the WIP control model of serial production line, a WIP control model under the PID controller in serial production line has been built. Finally, Using simulink soft simulate WIP control in car's door production line. The simulation results analysis show that the PID controller can effectively reduce and stabilize the WIP rather than P controller.Based on the above researches, the method of WIP control under the PID controller is useful in finding the problems in production logistics system control, it directs WIP control of discrete products manufacturing under the dynamic environments.