R.J.I. Basten

Pooling of spare parts between multiple users: How to share the benefits?

Companies that maintain capital goods (e.g., airplanes or power plants) often face high costs, both for holding spare parts and due to downtime of their technical systems. These costs can be reduced by pooling common spare parts between multiple companies in the same region, but managers may be unsure about how to share the resulting costs or benefits in a fair way that avoids free riders. To tackle this problem, we study several players, each facing a Poisson demand process for an expensive, low-usage item. They share a stock point that is controlled by a continuous-review base stock policy with full backordering under an optimal base stock level. Costs consist of penalty costs for backorders and holding costs for on-hand stock. We propose to allocate the total costs proportional to players’ demand rates. Our key result is that this cost allocation rule satisfies many appealing properties: it makes all separate participants and subgroups of participants better off, it stimulates growth of the pool, it can be easily implemented in practice, and it induces players to reveal their private information truthfully. To obtain these game theoretical results, we exploit novel structural properties of the cost function in our (S − 1, S) inventory model

Defining line replaceable units

Defective capital assets may be quickly restored to their operational condition by replacing the item that has failed. The item that is replaced is called the Line Replaceable Unit (LRU), and the so-called LRU definition problem is the problem of deciding on which item to replace upon each type of failure: when a replacement action is required in the field, service engineers can either replace the failed item itself or replace a parent assembly that holds the failed item. One option may be fast but expensive, while the other may take longer but against lower cost. We consider a maintenance organization that services a fleet of assets, so that unavailability due to maintenance downtime may be compensated by acquiring additional standby assets. The objective of the LRU-definition problem is to minimize the total cost of item replacement and the investment in additional assets, given a constraint on the availability of the fleet of assets. We link this problem to the literature. We also present two cases to show how the problem is treated in practice. We next model the problem as a mixed integer linear programming formulation, and we use a numerical experiment to illustrate the model, and the potential cost reductions that using such a model may lead to.

Understanding maintenance decisions : how to support acquisition of capital assets

This chapter contributes with theoretical and practical insights on maintenance decision making during acquisition of capital assets. We give theoretical insights about maintenance decision making by reviewing the literature, while our practical insights come from examples of the decisions made at a maintenance organization for rolling stock: NedTrain. We find that strategic maintenance decisions are more relevant before contracting than tactical or operational decisions, and they have the largest potential to impact Life Cycle Costs. The research on strategic maintenance decisions is too broad to review individual decisions, and therefore we review papers that structure decisions in the form of frameworks. We find that according to the literature, assets and their maintenance services should be developed concurrently. However, we find in practice that NedTrain’s approach is to fit new assets into the existing maintenance services, while there are parallel continuous improvement processes for those services. From practice, we conclude that strategic maintenance decisions are not concurrent to rolling stock design decisions. We also conclude that there is a need for methods and tools to support strategic maintenance decision making during early stages of acquisition, especially before contracting.

Maintenance Service Logistics

Capital goods, such as manufacturing equipment, trains, and industrial printers, are used in the primary processes of their users. Their availability is of key importance. To achieve high availability, maintenance is required throughout their long life cycles. Many different resources such as spare parts, service engineers and tools, are necessary to perform maintenance. In some cases, e.g. for trains, also maintenance facilities are required. Maintenance service logistics encompasses all processes that ensure that the resources required for maintenance are at the right place at the right time. In a broader sense, it also includes maintenance planning and design-for-maintenance. We first discuss capital goods and the requirements that their users have, which leads us to basic maintenance principles and the structure of typical service supply chains. Next, various relevant decisions and supporting theories and models are discussed. Finally, we discuss the latest developments within maintenance service logistics.