An Opportunistic Maintenance Decision of A Multi-Component System Considering the Effect of Failures on Quality

Preventive maintenance is a planned activity to keep the manufacturing facilities in good condition. However, because of limited time and resources, not all the system components can be repaired/replaced during the planned opportunity. When the system is under maintenance, it is very conservative to take the maintenance decision on the components because of limited available time and resources, hence the decision is selective. In this paper, an approach for opportunistic maintenance of a multi-component system is presented. The objective is to obtain a minimum cost solution with required availability and which can be accomplished within the allowable maintenance time. The optimization of the proposed model in this paper results into maintenance decision in terms of maintenance actions namely, repair, replace or donothing for the system components. A genetic algorithm approach is used for getting the optimal solution. The application of the model is demonstrated through a case study of a high pressure die casting machine. Keywords-Opportunistic maintenance, Multi-component system, Genetic algorithm, Rejection cost Nomenclature AReq : Required system availability Β : Weibull shape parameter for component η : Weibull scale parameter for component CC : Cost of component (Rs.) Cf : Failure cost per incident for component (Rs.) CLP : Cost of lost production (Rs.) CLM : Labour cost of maintenance (Rs./hr) Csp : Cost of sub-components and consumables (Rs.) CR : Replacement cost for component (Rs.) Cr : Repair cost for component (Rs.) CRL : Cost of loss of residual life (Rs.) E[DT]TPMS: Expected downtime in next operating period (hr.) ML : Mean life (hr.) MRL : Mean residual life (hr.) MTTrA : Mean time to repair for component (hr.) MTTRA : Mean time to replacement for component (hr.) MTTCA : Mean time to corrective action for component (hr.) PR : Production rate (units/hr.) RF : Restoration factor for component TPMS : Time between the current maintenance and next expected opportunity (hr.) TAvl : Time available to carry out maintenance (hr.) Manuscript received March 18, 2013; revised April 05, 2013. Pravin P. Tambe is a Research scholar in Mechanical Engineering Department at Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India (email:[email protected], Ph No: +91-11-26596317, Mobile: +91-9811873959, Fax: 91-11-26582053) Dr.Makarand S. Kulkarni is an Associate Professor in Mechanical Engineering Department at Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India (email: [email protected]) TLM : Time elapsed between the last maintenance and opportunity (hr.) TCf : Total cost of failures (Rs.) TCR : Total cost of replacement (Rs.) TCr : Total cost of repair (Rs.) (vi)O : Effective age at opportunity (hr.)