Opportunistic Preventive Maintenance Strategy On Series-parallel System Considering Line Balancing

In the current fast-paced industrial environment,more and more complex series-parallel manufacturing systems are required by the company to satisfy the production needs. The growing production scale, diversified equipment, complex system structure, random customer orders, all need the manufacturing system ran stately with the ensure reliability and minimum breakdown times. Proper maintenance schedule is required to improve manufacturing systems’ profitability and productivity. For now, the existing mature single machine maintenance strategy cannot satisfy the requirement of large production system with much equipment. Periodical preventive maintenance model barely consider the specification of the system and can easily result in the over-maintained or less-maintained. Recently, there has been a growing interest in modeling and optimization of multi-unit systems or series-parallel systems with the increasing demand from industry.This paper studies opportunistic preventive maintenance strategy for series-parallel manufacturing systems consist of different types of machines. During the maintenance strategy decision-making part, it will consider the system structure and production rate to keep the system and its machines operate in good condition and in a cost effective manner.First, an opportunistic preventive maintenance model aiming at serial-parallel machining line consisting of much equipment is developed. Considering the specificity of this system, the concept of line balancing is proposed to get better utilization of the equipment and balance the production capacity of each station. The opportunistic preventive maintenance model is based on reliability and makes a target of the minimal maintenance cost. Proper threshold values as well as the maintenance scheme are obtained by Monte Carlo Simulation of the model. An applied case shows that the model is practical and efficient to get a proper maintenance schedule for Series-Parallel System.Second, for serial-parallel manufacturing system with bottlenecks, theory of Constraints is used to differentiate the maintenance strategy of different machines from different stations, in order to ensure to maximize the utilization of machines from the bottleneck station. The opportunistic preventive maintenance model is based on reliability with a target of optimize the multi-objective which are minimal maintenance cost and maximize the production capacity of the whole system. Proper threshold values as well as the maintenance scheme are obtained by Monte Carlo Simulation of the model. An applied case shows that the model is practical and efficient to get a proper maintenance schedule for Series-Parallel System.Last, a comparison between the opportunistic preventive maintenance and periodical preventive maintenance is made by applied both strategies to the Series-Parallel flange plate production system. Analysis form different aspects like reliability, maintenance time and cost are given to show the applicability, advantages and disadvantages of these two strategies.