Spare Parts Logistics Research Articles

Developing the Additive Manufacturing Chain of AlSi7Mg with Laser Powder Bed Fusion and Tailored Heat Treatments for Railway Spare Parts

The use of metal additive manufacturing technologies in railways sector can provide increased flexibility in terms of spare part logistics. Combined with lightweight metals such as Al-alloys, the product performance can also be enhanced in terms of weight reduction, vibration and noise control. The railway sector is more likely to exploit large and bulky parts produced by laser powder bed fusion (LPBF), which should have appropriate mechanical properties. Therefore, the whole production chain should be analyzed considering the heat treatment steps suited for a distributed and resource efficient manufacturing scheme. Accordingly, this work analyzes the additive manufacturing of AlSi7Mg alloy by LPBF and its consecutive heat treatment steps. In particular, the impact of LPBF process productivity, heat treatment type and atmosphere composition were considered to analyze the most appropriate route for the needs of the railways applications. The results show that with an appropriate direct aging treatment in air, mechanical characteristics of the alloy could be improved, despite that the high layer thickness used in LPBF could increase process productivity. The absence of a quenching step was found to be favorable for large parts, while the absence of an inert gas such as Ar in the heat treatment did not generate any reduction in the mechanical properties.

Designing resilient military logistics with additive manufacturing

PurposeIn this study, the authors explore how novel and relevant technologies can change the overall design of systems, and which factors influence the design of resilient systems in particular. After evaluating the effects of these factors, the authors describe the potential role of AM-supported maintenance operations in military logistics and draw broader conclusions regarding designing for resilience.Design/methodology/approachThe authors build a simulation model of the AM-supported maintenance capability of a mechanised battalion to analyse factors affecting its resilience. AM production capacity specifically refers to metal printing and was verified by data generated from 3D printing of the actual APC parts.FindingsThe current AM speed is not able to increase resilience at the depot level, so at present, increasing the spare parts inventory is a better way to improve resilience. However, with future improvements in speed the AM may become feasible in battlefield maintenance.Practical implicationsAM holds great promise in increasing resilience of especially the spare part logistics. At present technology, it is not yet fully realised in the case.Originality/valueThe authors suggest a concrete system performance measure, where reaching a concrete limit, system resilience is lost. The authors present arguments for a definition of resilience where pre-disruption activities are not part of resilience. The authors maintain that simulation, with its ability to include detail, is well-suited in design-for-resilience because supply chains are context dependent and disruptions unexpected.

Application of 5s Methodology: A Case Study Towards Enhancing Spare Parts Processing Efficiency

This study investigates the significance of the 5s methodology and its applications in the efficient development of spare parts logistics and the handling of warehouse processes in the petroleum industry. The Delphi approach was used to obtain expert judgment opinion through a series of questionnaires. The information collected was assessed by a selected panel of experts to gather their consolidated opinion and propose their weighted final judgment. The Gemba walk approach was also used as a tool to describe the personal observation of the executed tasks based on random cross-checks of the interaction between senior staff and their employees to explore opportunities for continuous improvement. The results indicate that employee commitment toward implementing the 5s methodology contributes significantly to improve the processing of spare parts in a warehouse. Furthermore, the analysis exhibited 90.1% efficiency in the spare parts logistics in successive months. The results shows that 5s methodology improve the efficiency of the spare parts processing time in the warehouse and recommend the standardize pillar to be implemented weakly compared to the other four 5s pillars. The study shows the relevance of employees’ commitment toward using the 5s methodology to enhance the continuous improvement initiatives of the spare part logistics. This study explores the significance of the 5s methodology in improving the spare parts logistics in a warehouse and its use to overcome their deficiencies and improving the maintenance activities. It also seeks to eliminate downtime cost while improving safety, quality, and efficiency within the available resources. The research could help managers, operations professionals, and researchers investigate warehouse issues in many other industries.

Evaluation of the energy demands for a floating O&M-hub

The Energyhub@Sea concept is one of the four research applications of the Space@Sea project funded by the EU’s Horizon 2020 research program (GA number: 774253). The focus of this paper is the evaluation of the energy demands of an energy self-sufficient maintenance platform at the location of Helgoland in the North Sea. In view of this, a standardized modular floater was developed as an offshore wind operation and maintenance base, which in the following paper is referred to as an O&M hub. The O&M hub is intended to be equipped with accommodation facilities and various renewable energy infrastructure as well as spare parts logistics, enabling the platform to perform maintenance of offshore gearless wind turbines with a capacity of up to 10 MW. To be energy self-sustaining, an energy supply system for the hub was developed and simulated at a resolution of ten minutes by means of the Top-Energy simulation software, a commercial software tool. As a basis for the simulation, an approach for the automated determination of flexible load profiles, in resolutions of up to ten minutes was developed. This load profile generator creates load profiles on the basis of environmental conditions, technical characteristics, and expected behaviors of the inhabitants. On the basis of the generated load profiles, a first layout (referred to as baseline scenario) for the different components of the energy system was evaluated and tested through simulation. In a second step, three optimization scenarios were developed and simulated with regards to the financial feasibility of the Energyhub.

Demand forecasting methods for spare parts logistics for aviation: a real-world implementation of the Bootstrap method

One of the critical issues that an airline faces in its day-to-day operations is a correct prognosis of the necessary quantity of spare parts that are continuously fed into unexpected maintenance operations. Indeed, there is a critical need for accurate forecasting methods to predict the demand of these spare parts in order to minimize the so-called Aircraft-On-Ground situations. This paper describes the real-world implementation of the Bootstrap method and the assessment of its performance with actual data from aviation logistics. The analysis reveals that the Bootstrap method, while not the most accurate in every case, should be preferred over other popular methods in spare parts forecasting for aviation, because is more agile and can address adequately all categories of demand. A simple decision support system is then presented to assist airline materials managers in using the bootstrap method. The system is expandable and can potentially incorporate other forecasting method as well.

The after-sales strategy of an industrial equipment manufacturer: evaluation and control

PurposeThe purpose of this study is to evaluate the after-sales strategy of an industrial equipment manufacturer.Design/methodology/approachThe research study’s object is the Brazilian operation of a company belonging to a multinational group that designs, manufactures and installs technology-based equipment. The research method is qualitative modeling with a quantitative analysis. A literature review and a focus group with managers organized the after-sales strategy of the company in four constructs measured by 24 indicators. The constructs are technical assistance (TA), reliability management (RM), customer relationships (CRs) and spare part logistics (SL). A total of seven managers evaluated the importance and performance of the indicators.FindingsTA, RM and CRs are lagging constructs (the importance is greater than the performance), whereas SL is a leading construct (the opposite). The study proposed four strategic actions that change the type of emphasis that the company poses to service: from in-house to field maintenance service, from correction to prevention reliability improvement, from technical- to customer-focused relationships and from direct to integrated logistics service.Research limitations/implicationsThe study limits to the case of a technology-based manufacturing company.Practical implicationsThe strategic movement reallocates resources from leading indicators to lagging indicators in a sharp, clear movement of forces in the company.Originality/valueThe main contribution is a structured method to evaluate and control the strategic performance of an industrial equipment manufacturer in after-sales activities.

Integrated Health Monitoring for the actuation system of high-speed tilting trains

Tilting trains are designed to reach high speed on pre-existing railroads without the need of adjusting the tracks geometry or building dedicated lines; the tilting of the carbody keeps an acceptable level of comfort by limiting the lateral acceleration felt by passengers when the train runs along curved tracks with speed higher than the balance speed built into the curve geometry. As such, they are often used to reduce travel times on routes with several curves. Tilting is performed through a position-controlled actuation system which operates according to the commands received from the train control system: in the studied configuration, the torque needed to tilt the car body with respect to the bogie is provided by a series of hydraulic actuators, while the position information used to close the control loop comes from two capacitive sensors located in the front and rear part of each vehicle. Tilt angle measurement is vital for the system operation and for ensuring a safe ride; the traditional solution in case of discrepancy between the signals of the two tilt angle sensors of any vehicle is to disable the tilting function while limiting the train speed to avoid issues during changes of direction. In a similar fashion, the failure in one (or more) of the tilting actuators would result in the loss of the tilting capability and the return to a fixed configuration operating at reduced speed. It should be noticed that the negative impact of the loss of the tilting system is not limited to the faulty train, since it might affect the entire traffic schedule on the interested lines. The paper presents an integrated Health Monitoring framework that makes intelligent use of all available information thus enhancing the system availability, allowing its operation even in presence of faulty sensors and detecting the onset of failures in the actuation system. At the same time its use can facilitate maintenance organization, simplify the spare parts logistics and provide help to the traffic management. The proposed framework has been developed taking advantage of a high-fidelity model of the physical system validated through comparison with experimental mission profiles on the Lichtenfels - Saalfeld and Battipaglia - Reggio Calabria routes, which have been used by the train manufacturer to assess the performance of their tilting trains.

Modeling and long-term forecasting demand in spare parts logistics businesses

In order to provide high service levels, companies competing in the electronics manufacturing sector need to ensure the availability of spare parts for repair and maintenance operations. This paper examines the purchase life-cycles of electronic spare parts and presents a new way of modeling and forecasting spare part demand for electronic commodities in the spare parts logistics services. The presented modeling methodology is founded on the assumption that the purchase life-cycles of spare parts can be described by a curve with short term fluctuations around it. For this purpose, a flexible Demand Model Function is introduced. The proposed forecasting method uses a knowledge discovery-based approach that is built upon the combined application of analytic and soft computational techniques and is able to indicate the turning points of the purchase life-cycle curve. The novelty lies in the fact that the model function has certain characteristics which support describing and interpreting the demand trend as a function of time. The application of our methodology is mainly advantageous in long-term forecasting, it can be especially useful in supporting purchase planning decisions in the ramp-up and declining phases of purchase life-cycles of product specific spare parts. A demonstrative example is used to illustrate the applicability of the proposed methodology. Its forecasting capability is compared to those of some widely applied methods in business practice. From the results, the new method may be viewed as a viable alternative spare part demand forecasting technique in spare part logistics sector.

Stock or Print? Impact of 3D Printing on Spare Parts Logistics

We present a general framework to analyze and quantify the impact of 3D printing on spare parts logistics. We consider multiple parts facing stochastic demands. To minimize long-run average system cost, our model determines which parts should be printed and which should be stocked and the corresponding base-stock levels. When a demand for a stocked part encounters a stockout, it can either be backlogged or overflowed to the 3D printer. We derive various structural properties and characterize the optimal policy for several special systems, which lead to efficient near-optimal heuristic solutions for the general system. We demonstrate that adopting 3D technology can yield significant cost savings and this impact increases in part variety. Also, “a little flexibility goes a long way” in the sense that allowing both the stock and print options can substantially slash system inventory and cost, while the utilization of the 3D printer is surprisingly low.

Stock or Print? Impact of 3-D Printing on Spare Parts Logistics

We present a general framework to study the design of spare parts logistics in the presence of three-dimensional (3-D) printing technology. We consider multiple parts facing stochastic demands and adopt procure/manufacture-to-stock versus print-on-demand to highlight the main difference of production modes featured in traditional manufacturing and 3-D printing. To minimize long-run average system cost, our model determines which parts to stock and which to print. We find that the optimal 3-D printer’s utilization increases as the additional unit cost of printing declines and the printing speed improves. The rate of increase, however, decays, demonstrating the well-known diminishing returns effect. We also find the optimal utilization to increase in part variety and decrease in part criticality, suggesting the value of 3-D technology in tolerating large part variety and the value of inventory for critical parts. By examining the percentage cost savings enabled by 3-D printing, we find that, although the reduction in printing cost continuously adds to the value of 3-D printing in a linear fashion, the impact of the improvement of printing speed exhibits S-shaped growth. We also derive various structural properties of the problem and devise an efficient algorithm to obtain near optimal solutions. Finally, our numerical study shows that the 3-D printer is, in general, lightly used under realistic parameter settings but results in significant cost savings, suggesting complementarity between stock and print in cost minimization. This paper was accepted by Victor Martínez-de-Albéniz, operations management.

Dynamic spare parts transportation model for Arctic production facility

Timely delivery of the required spare parts plays an important role in meeting the availability target and reducing the downtime of production facilities. Spare parts logistics is affected in complex ways while operating in the Arctic, since the area is sparsely populated and has insufficient infrastructure. It is also greatly affected by the distinctive operational environment of the region, such as cold temperature, varying forms of sea ice, blizzards, heavy fog, etc. Therefore, in order to have an effective logistic plan, the effect of all influencing factors, called covariates, on the transportation of the spare parts need to be identified, modelled and quantified by the use of an appropriate dynamic model. The traditional models, however, lack the comprehensive integration of the effect of covariates on the spare parts transportation. The purpose of this paper is to introduce the concept of a dynamic model for spare parts transportation in Arctic conditions by considering the time-independent and time-dependent covariates. The model continuously updates the prior probabilities according to the most recent time-dependent covariates to provide posterior probabilities. The application of the model is illustrated using a case study.

Integrated spare parts logistics and operations planning for maintenance service providers

This paper considers the problem of coordinated spare-part logistics and operations planning for third-party maintenance providers. Due to the multi-indenture structure of the equipment, different types of components might randomly fail to perform at different points of time. The spare part logistics literature has been focused on spare part inventory management in an in-house maintenance context. In this article, a mathematical programming model is first developed to formulate the problem in the context of a third-party maintenance provider who is faced with strict due dates for the delivery of repaired equipment. The model seeks the optimal number of maintenance jobs that can be completed to deliver at each period, as well as the order quantity of spare parts so as to minimize the procurement, inventory, and equipment late delivery costs, while taking into account the spare part supply lead-time. Next, we model the spare part demand uncertainty as a non-stationary stochastic process in each period in the planning horizon. The deterministic model is then reformulated as a multi-stage stochastic program with recourse. We also discuss the complexity of the stochastic model and propose a preprocessing approach to reduce its size for large instances. Numerical results demonstrate how the proposed model links the spare part logistics and equipment delivery decisions under spare part demand uncertainty.

Towards Autonomous Control in Maintenance and Spare Part Logistics – Challenges and Opportunities for Preacting Maintenance Concepts

Maintenance and spare part logistics often determine the life cycle costs related to the usage phase of assets. Therefore, different maintenance strategies are known from literature and adopted by enterprises in order to cut these costs. Most often these strategies face problems due to uncertainties in processes and tasks. This paper suggests an adjusted preactive maintenance concept which implements autonomous control aspects in order to plan and control personnel, equipment, resources, etc. ad hoc and without hierarchical planning instances. In doing so, different well known strategies will be kept equitable within the concept but are replenished with an overall heterachical organized planning and controlling approach. As a result, maintenance objects themselves gain the opportunity to trigger maintenance measures, no matter whether it's a case of inspection, maintenance or repair, according to their particular requirements. The paper gives a valuable insight into an effective concept of how to handle the complex situation for the operational maintenance processes as well as related spare part logistics in general and illustrates first concrete approaches.

Maintainability analysis of an offshore gas compression train system, a case study

PurposeThis paper aims to propose a practical method of performing maintainability analysis of an offshore system at operation phase having some improvement trend.Design/methodology/approachThe analysis follows a systematically developed method of analyzing maintenance data, identifying critical factors affecting system performance, and developing suitable downtime distribution model with some applications of statistical analysis techniques and expert opinion.FindingsImprovement in spare part logistics is found significant in reducing downtime thus should be well feedback to design and plant engineers so that it can be incorporated in new offshore system. The downtime models developed based on the steady state analysis and expert input are found to be practical for prediction of the system maintainability performance.Research limitations/implicationsThe analysis focuses on the downtime which includes the repair, logistics and administrative delay time. At the operation phase, plant personnel are mostly interested in the availability and downtime performance of the system thus this study provides an excellent example of how the analysis can be done practically and effectively.Practical implicationsMaintainability analysis at operation phase is crucial to assess and predict the maintenance system performance and provide valuable feedback to the design phase and existing plant for further improvement. The methodology developed here is practical hence can assist plant personnel to perform maintainability analysis effectively.Originality/valueThis paper present a generic method of analyzing maintainability at the operation phase. The proposed distribution method via steady state and expert input approaches provides a practical method for formulating downtime distribution model when improvement trend exists.

A Conceptual Model for the Simulation-Based Analysis of the Operational Planning of Spare Parts Supply Chains

Maintenance is critical to the reliability of manufacturing processes and thus for the economic performance of industrial companies. For supporting an effective maintenance, spare parts logistics have to deliver necessary parts on the right moment for the maintenance service to be executed. For analysing the effectiveness of the operational planning of spare parts supply chains, simulation approaches can help to recognize the impact of changes made to the operation rules of the system. More remarkably, its application can assist managers in the decision making process on complex problems and enable a better understanding of processes. Taking into consideration current state-of-the-art concepts and models for the operational planning of supply chains and the application of simulation techniques for the analysis of complex systems, this paper aims to propose a conceptual model for the simulation-based analysis of the operational planning of spare parts supply chains.

Potential development targets in spare part logistics

The study reviews development actions carried out in maintenance and spare part services. The review focuses on case studies and other real-life examples that have been reported on. It is also discussed how to identify the situations where it is practicable to emulate the found development actions. An illustrative case example is used to demonstrate how to evaluate the suitability of some of the development approaches in practice. The summary may offer ideas for companies that are in early phases of their development work, and practical guidelines for evaluating the suitability of some development actions.

A Strategic Framework for Spare Parts Logistics

Strategically aligned and efficiently implemented spare parts logistics can differentiate a business from its competitors, lower costs, increase revenues, and thus help firms generate greater value for customers and ultimately increase profits. Based on multiple case studies with manufacturers in the machine and plant construction industry, this article examines the key components of a superior spare parts logistics strategy. The study suggests that an efficient spare parts logistics strategy can be developed with a three-step model that consists of nine components.

On the use of installed base information for spare parts logistics: A review of ideas and industry practice

Demand for spare parts is often difficult to forecast using historical data only. In this paper, we give an overview of installed based management and provide several ways in which installed base information can be used to support forecasting. We discuss cases where installed base information is used in forecasting at four companies and list the issues involved. Moreover, we review some models to illustrate the potential value of the installed base information and conclude that forecasts of spare parts demand and return can be made considerably more timely and accurate using installed base information.

Spare parts logistics for the Chinese market

PurposeDespite the proven benefits of high‐performing spare parts logistics, recommendations on how to organize spare parts logistics in China are rather rare. The absence of spare parts logistics concepts for China is surprising, since the spare part business is the profit pool of the capital goods industry: spare parts create about 17 percent of the industry's total revenue. The margins involved in this spare parts revenue are, on average, 25 percent compared to 2‐3 percent of the capital goods. This paper aims to offer recommendations to increase spare parts logistics performance.Design/methodology/approachThe authors conducted an extensive benchmarking project with a variety of firms (focus group and single case study) in order to gain a better understanding of spare parts logistics in China. By reviewing the first benchmarking findings with a single company that struggled to achieve sufficient spare parts logistics performance, additional insight was gained into how spare parts logistics should be organized in China.FindingsThe paper attempts to provide a better understanding of the necessary changes for improving logistics performance in the Chinese market. It analyzes the necessary changes to achieve a cutting‐edge logistics solution, and shows how companies can implement the solution.Research limitations/implicationsResearch limitations come from the qualitative nature of the research.Practical implicationsManagers can use the results obtained in this study to challenge their current logistics practices and develop a project procedure on how to initiate logistics projects that lead to cutting‐edge logistics performance.Originality/valueRather than concentrating on performance benchmarks of the supply chain of spare parts or specific aspects of spare parts management, the paper develops the setting up of a cutting‐edge logistics solution for China and Asia. The cutting‐edge solution is based on two main pillars: companies should try to develop logistics solutions for Asia that consider existing Asian and Chinese constraints instead of taking the logistics practices used in mature markets and trying to adapt them to the Chinese market, and the development of the logistics solution should be in intensive collaboration with the logistics providers.

Spare parts logistics and installed base information

Many of the challenges in spare parts logistics emerge due to the combination of large service networks, and sporadic/slow-moving demand. Customer heterogeneity and stringent service deadlines entail further challenges. Meanwhile, high revenue rates in service operations motivate companies to invest and optimize the service logistics function. An important aspect of the spare parts logistics function is its ability to support customer-specific requirements with respect to service deadlines. To support customer specific operations, many companies are actively maintaining and utilizing installed base data during forecasting, planning and execution stages. In this paper, we highlight the potential economic value of installed base data for spare parts logistics. We also discuss various data quality issues that are associated with the use of installed base data and show that planning performance depends on the quality dimensions.