Study On Preventive Maintenance Policy Based On Reliability

Being a key management activity to improve the equipment reliability and insurethe effective operation of the equipment, the growing importance of which attractsincreasing attention to search the optimal maintenance strategy for manufacturingsystems, with the purpose of cutting down maintenance and production costs as well asenhancing competitiveness. With the increasing complexity of manufacturing systemsand faster demand of production lead time, the traditional maitenance managementfocusing on single equipment or ignoring production scheduling is facing newchallenge.This dissertation studies the reliability-based equipment preventive maintenanceoptimization problems for the manufacturing system.The main contents of thisdissertation are as following:1. An improvement factor is developed to describe the effect after preventivemaintenance, then a preventive maintenance model with reliability constraints for thesingle equipment system is proposed,with the objective of minimizing the totalproduction costs of the production system. Finally,a numerical example followingWeibull distribution optimized with genetic algorithm is discussed,and the change ofsystem's optimal preventive maintenance period and maintenance rate along withreliability constrain is researched.2. Extends the single equipment system to the multi-equipment system,andconduct design for the reliability-based equipment optimal preventive maintenancepolicy for parallel and series systems. With that,an optimal research model satisfied thereliability constrain in finite time horizon for the parallel system based on hybridimprovement factor is presented,achieving the value of preventive maintenancereliability threshold of each parallel equipment. After that,taking into account theeconomic dependence in a flow-shop manufacturing system,consisting of differentequipments. To develop the reliability-based opportunistic preventive maintenancemodel, a judgment factor and a reason factor are introduced to describe the workingstate of the system and to explain the reasons for system downtime,so as to search forthe optimal maintenance strategy for the series system.3. To improve the method that studied preventive maintenance and productionscheduling independently,a kind of new policy integrating both two is proposed. Thenintegrated models based on this policy meetting the reliability constraint are bulit for a parallel system and a flow-shop system,to minimize the total cost consisting ofworkpiece delay cost,maintenance cost and downtime loss. The results show that thisoptimal integrated policy is much more practical than the optimal maintenance planningand production scheduling decision given by the independent models, and it can providedecision support for complex production system.