Multi-attribute classification method for spare parts inventory management

In this paper a new approach for spare parts multi-dimensional classification is presented. Inventory constraints, costs of lost production, safety and environmental objectives, strategies of maintenance adopted, logistics aspects of spare parts are some of the criteria taken into account, and spare parts classification is thus defined with respect to multiple attributes. Following a basic idea of reliability centered maintenance (RCM) approach, the methodology represents a structured framework based on a decision diagram which guides the analyst toward the most appropriate final class and corresponding to the different levels of criticality of the item. In virtue of the large number of the potential operational characteristics to be considered, the diagram is also integrated with a set of analytic hierarchy process (AHP) models used to solve the various multi-attribute decision sub-problems at the different levels/nodes of the decision tree. These AHP models make it possible to classify, at each node of the diagram, the spare parts in different categories of risk such as Critical, Important, and Desirable. Following this approach, during the decision process a total number of 17 different attributes are considered and analysed in an easy and rational manner, avoiding the use of over-complex and large decision trees or AHP models. Finally, an Inventory Policy Matrix is defined to link the different classes of spare parts with the possible inventory management policies so as to identify the “best” control strategy for the spare stocks. The principles of the theory and an actual application in a company operating in the paper industry are reported in the paper.