Study On Efficiency-oriented Equipment Preventive Maintenance Modeling

Reasonable preventive maintenance(PM)is an essential way for manufacturing systems to ensure the good operational condition.On the one hand,the development of automation,precision and increasing complexity of manufacturing systems,is accompanied by the requirements for the professional,timeliness,and economy of equipment maintenance.As a result,the input for PM exhibits an increasing trend since performing PM usually requires expensive tools and professional technicians.On the other hand,due to the increasing demand for quality,production,and availability of production equipment,maintenance and repair services should aim to make sure that the equipment performs well and the quality of output products is stable.Therefore,it is urgent for the enterprises to minimize the input costs of maintenance activities while ensuring the stable output of production equipment.The principle of matching input and output must be fully considered while formulating maintenance strategies.This paper proposes a new efficiency-oriented preventive maintenance(PM)model for machining equipment to establish a tradeoff between the input and output of maintenance according to the actual needs of the new situation.A multi-attribute index is firstly introduced to evaluate the value of maintenance where the attributes of system availability and product qualification rate are comprehensively considered.By investigating the influencing mechanism of deteriorating quality-related components on the equipment's failure rates and the product quality degradation,the multi-objective maintenance efficiency function was established on the indexes of the equipment's availability based on the proportional hazard model and the product qualification rate based on the response model,the weight coefficients of which were allocated according to the amount of products affected by 1% change of each index.The weights for the attributes are dynamically and quantitatively allocated according to the number of products affected by each attribute's unit change.The maintenance efficiency is then defined as the quotient of the value of maintenance divided by the direct cost of maintenance including PM cost and minimal repair cost.Finally,according to the varied internal repair process of the equipment,the maintenance effect is modeled,and the periodic PM policy and failure limit policy are used to model the preventive maintenance strategy.The optimal maintenance plan is obtained by maximizing the maintenance efficiency function.Numerical examples are given to verify the effectiveness of the model.This paper establishes a multi-objective maintenance efficiency function and equipment preventive maintenance model to maximize the output of equipment maintenance costs,thus providing a new way of maintenance modelling and decision-making for the enterprise.