Spare Parts Logistics Research Articles

OPTIMIZING JOINT MAINTENANCE AND STOCK PROVISIONING POLICY FOR A MULTI-ECHELON SPARE PART LOGISTICS NETWORK

ABSTRACT Spare part stock management attempts to ensure that the failed equipment items can be replaced immediately to maintain a sufficient productivity level. In maintenance, the inventory policy determination for spare parts is an important issue. The age-based preventive replacement policy may seek the least total cost for spare part replacement. Considering the criticality of equipment where it is installed, demand for a certain spare part can be categorized into critical and non-critical. The stock level for critical demand can be set to reserve certain spare parts in stock for critical equipment users. This stock policy is named the inventory rationing policy. The stock policy has a significant impact on production system performance, particularly when a machine breakdown causes a large amount of production lost. This study optimizes the joint age-based preventive replacement and inventory rationing policy in a multi-echelon spare part logistics network. In this study, there are equipment users, spare part distribution center and spare part suppliers in the multi-echelon system. Inventory policy optimization for the spare part logistics network is extremely complicated. This paper adopts the scatter search based simulation-optimization method to obtain the optimal configurations with respect to maximizing the total profit of the spare parts logistics network. An implementation example of a spare part logistics system is used to demonstrate the advantages of employing the joint policy.

An Approximation Algorithm for a Large-Scale Facility Location Problem

We developed a new practical optimization method that gives approximate solutions for large-scale real instances of the Uncapacitated Facility Location Problem. The optimization consists of two steps: application of the Greedy—Interchange heuristic using a small subset of warehouse candidates, and application of the newly developed heuristic named Balloon Search that takes account of all warehouse candidates, and runs in ( O (3n + 2n log n ) ) expected time (n is the number of nodes of the underlying graph). Our experiments on the spare parts logistics of a Japanese manufacturing company with 6000 customers and 380,000 warehouse candidates led us to conclude that the Greedy heuristic improved the total cost by 9%-11%, that the Interchange heuristic improved the total cost by an additional 0.5%—1.5%, and that Balloon Search improved it by a further 0.5%—1.5%.

Maintenance spare parts logistics: Special characteristics and strategic choices

The diversity of the operational control characteristics of spare parts is taken as a basis for supporting the planning and designing of a spare parts logistics system. Four control characteristics of maintenance spare parts – criticality, specificity, demand pattern, and value of parts – are discussed in terms of their effects on logistics system elements – network structure, positioning of materials, responsibility of control, and control principles. Distinct operating policies for different types of parts in the spare parts supply chain are illustrated.

Benchmarking for spare parts logistics

This article shows the use of benchmarking for the spare parts logistics in the German mechanical industry (investment goods or capital goods). After pointing out the areas of benchmarking application, the use of total function deployment (TFD) for the evaluation of benchmarking metrics is explained. With TFD customer requirements on spare parts supply and the process structure of spare parts logistics are brought together in quality matrices, which are the bases for the metrics derivation. The last paragraph contains the results of a survey in the German mechanical industry. Concrete values of benchmarking metrics from the questioned companies, belonging to metrics on delivery service, costs of logistics and on materials management, are given. All theoretical and empirical results are drawn from a research project conducted in the Institute of Business Administration/Department of Business Management at Darmstadt University of Technology.

Near-Optimal Service Constrained Stocking Policies for Spare Parts

Consider a facility that stocks various parts in support of repairs for a set of products in some customer region. The problem considered is to determine base stock policies for each part to minimize expected inventory costs across all parts while satisfying some service constraint on total customer repair services completed. A heuristic procedure is developed for several variants of this problem. The heuristic is based on duality theory and is shown to have a close connection to the well known Greedy Heuristic. Encouraging experimental results on the performance of the proposed heuristic are reported. The basic problem structure considered is similar to the tool-kit problem, but it is formulated to allow applications in much broader spare part logistics contexts.

Spare Part Logistics Systems in West German Industries: An Empirical Analysis

One of the significant features of modern economies is the extensive use of technical equipment throughout production and consumption. Defects and malfunctioning of technical products result in various extra costs in terms of interrupted production as well as lost utility and additional expenses in private households. These consequences of product failures are amplified by the interdependencies within our economic system. Following an initiative by the Federal Association of Logistics Germany (Bundesvereinigung Logistik e.V.) an investigation of spare part logistics systems (SPLSs) in a number of West German industries was just completed. The research concentrated particularly on car, truck, and farming vehicle manufacturing, household appliances, audio and television equipment, and machinery. Our attention was focused on the structure and the functioning of SPLSs, in particular, whether to make or to buy a SPLS, which efficiency standards are employed and what kind of reorganisation had taken place during recent years.