Maintenance Decision Support for Manufacturing Systems Based on the Minimization of the Life Cycle Cost

The reduction of the overall Life Cycle Costs (LCC) is a key issue in manufacturing sector. Among the various contributions to LCC an important part is due to Reliability and Maintainability (R&M) issues and therefore a substantial reduction in LCC can be achieved by a conscious decisions and planning. Besides the failure and repair characteristics, the R&M related costs vary according to the maintenance strategy and policy selected for each components that form the manufacturing system. The aim of this paper is to describe a mathematical model that takes into account the R&M related fraction of the LCC in order to compare scenarios in which different maintenance strategies and policies are applied on the components of manufacturing systems. The calculations cover three policy possibilities: internal crew, external service (on-demand) and external service (annual contract). Both scheduled (preventive maintenance, inspection-based maintenance) and unscheduled (corrective maintenance, condition monitoring) strategies are considered. On the basis of the proposed formulae, optimization is carried out with a view to find the best solution in economical aspect. Furthermore, the method takes into account the possibility of clustering the scheduled interventions with the intention of reaching a predefined availability constraint while keeping the costs as low as possible. The paper presents the results of the European FP7 research project EASE-R3 where a specific maintenance planning software tool is being developed implementing the methodologies outlined above.