Spare Parts Planning Decisions

An important issue related to maintenance management is the problem of sizing the amount of spare parts. An excess number of spare parts results in financial losses. However, a lack of spare parts is also negative, because this may result in a loss of production due to the increased downtime of equipment. Therefore, spare parts should be available in quantity and at the right time. Spare part planning decisions need to evaluate multidimensional objectives, such as costs, profitability, reliability, availability and probability of stockout. Typically, these objectives are conflicting. Unlike a single objective approach, which often implies the poor performance of other objectives desired by the decision maker (DM), a multicriteria (MCDM/A) approach provides a spectrum of compromise solutions, which reflect the tradeoffs represented by DM’s preference structure, by using a multi-attribute utility function. Another relevant aspect is the management of uncertainties about the reliability or maintainability of the system, using the concepts of Decision Theory and a Bayesian approach, which incorporate experts’ prior knowledge. This chapter presents a model, based on Multi-attribute Utility Theory (MAUT), for spare parts sizing that considers aspects of the risk of inventory shortages and cost. Furthermore, an NSGA-II multi-objective model for multiple spare parts sizing is discussed. Finally, a model considering condition-based maintenance (CBM) is presented.