The influence of additive manufacturing on the configuration of make-to-order spare parts supply chain under heterogeneous demand

Additive manufacturing (AM), alongside technological developments, has been used in the production of spare parts with positive results for spare parts supply chains. In this study, we investigate spare parts supply chains serving heterogeneous demands from multiple service locations under the mode of make-to-order. We aim to compare different configurations (i.e. centralised and distributed) of spare parts supply chains in terms of their performance (e.g. sojourn time and cost) and to further propose suggestions to better configure AM-based spare parts supply chains by effectively allocating AM machines at service locations (SLs) or regional distribution centres (RDCs). In order to realise these research objectives, the simulation approach is used as the main research method. Different from the existing perception, our results illustrate that the distributed deployment of AM machines does not always guarantee a quick response, and that centralised configuration is desirable when the demand rate is relatively high due to the pooling effect. The distributed configuration, however, can still be suitable, considering the development of AM technology. Our results also indicate the possibility of a mixed configuration of AM-based supply chains with the potential for outperforming the purely centralised/distributed configuration. The criteria to design such a mixed configuration are also offered.     

Selective laser melting raw material commoditization: impact on comparative competitiveness of additive manufacturing

The paper analyses the impact of cheaper metal powder supplies on the comparative competitiveness of additive manufacturing (AM). By utilising two case studies, we compare the economic impact of an innovative titanium extraction method on Selective Laser Melting (SLM) and conventional methods of machining and casting. A switch-over analysis identifies the production quantities above which conventional manufacturing is more cost competitive than additive manufacturing. This analysis is performed for current raw material as well as cheaper raw material supply. The results illustrate the improved comparative competitiveness of SLM as the titanium supply is commoditised and more readily available in powder form. The responsiveness of the supply chain is improved as the switch-over point between SLM and conventional methods increases. Moreover, as the raw material supply chain for titanium is transformed through the use of this novel extraction method, the manufacturing supply chain is simplified.     

Scheduling of recovery actions in the supply chain with resilience analysis considerations

Supply chain engineering models with resilience considerations have been mostly focused on disruption impact quantification within one analysis layer, such as supply chain design or planning. Performance impact of disruptions has been typically analysed without scheduling of recovery actions. Taking into account schedule recovery actions and their duration times, this study extends the existing literature to supply chain scheduling and resilience analysis by an explicit integration of the optimal schedule recovery policy and supply chain resilience. In particular, we compute a schedule optimal control policy and analyse the performance of this policy by varying the perturbation vector and representing the outcomes of variations in the form of an attainable set. We propose a scheduling model that considers the coordination of recovery actions in the supply chain. Further, we suggest a resilience index by using the notion of attainable sets. The attainable sets are known in control theory; their calculation is based on the schedule control model results and the minimax regret approach for continuous time parameters given by intervals. We show that the proposed indicator can be used to estimate the impact of disruption and recovery dynamics on the achievement of planned performance in the supply chain.     

In search for classification and selection of spare parts suitable for additive manufacturing: a literature review

This paper reviews the literature on additive manufacturing (AM) technologies and equipment, and spare parts classification criteria to propose a systematic process for selecting spare parts which are suitable for AM. This systematic process identifies criteria that can be used to select spare parts that are suitable for AM. The review found that there is limited research that addresses identifying processes for spare parts selection for AM, even though companies have identified this to be a key challenge in adopting AM. Seven areas for future research are identified relating to the methodology of spare parts selection for AM, processes for cross-functional integration in selecting spare parts for AM, broadening the spare parts portfolio that is suitable for AM (by considering usage of AM in conjunction with conventional technologies), and potential impact of AM on product modularity and integrality.     

Modelling and solving spare parts supply chain network design problems

Spare parts are key operational assets in order to minimise unexpected equipment downtimes that may significantly impact a company’s results. The spare parts supply chain network supports the entire spare parts operations management and it is essential to achieve the planned goals. However, most of the traditional literature on spare parts management has not focused on the underlying supply chain network. Thus, this paper studies the integration of supply chain network design and control with traditional spare parts management. In particular, a generic network optimisation modelling structure is proposed, with simultaneous optimisation of warehouse locations and inventory control decisions, allowing minimising the total costs associated with the spare parts supply chain network. The generic model is specified based on three inventory control policies widely employed in the industry, which are suitable for managing a great variety of spare parts, i.e. (s, Q), (R, s, S) and (S-1, S). Furthermore, a solution approach is proposed based on Generalised Benders Decomposition. Finally, numerical results from a real-world application case in the process industry are shown and discussed.     

Revealing interfaces of supply chain resilience and sustainability: a simulation study

Dynamics of structures and processes is one of the underlying challenges in supply chain management, where multiple dimensions of economic efficiency, risk management and sustainability are interconnected. One of the substantiated issues in supply chain dynamics is resilience. Resilience has a number of intersections with supply chain sustainability. This paper aims at analysing disruption propagation in the supply chain with consideration of sustainability factors in order to design resilient supply chain structure in regard to ripple effect mitigation and sustainability increase. Ripple effect in the supply chain occurs if a disruption at a supplier cannot be localised and cascades downstream impacting supply chain performance. This simulation-based study helps to identify what sustainability factors mitigate the ripple effect in the supply chain and what sustainability factors enhance this effect. The results indicate that (i) sustainable single sourcing enhances the ripple effect; (ii) facility fortification at major employers in regions mitigates the ripple effect and enhances sustainability; and (iii) a reduction in storage facilities in the supply chain downstream of a disruption-risky facility increases sustainability but causes the ripple effect.     

Bullwhip effect and inventory oscillations analysis using the beer game model

This work examines the bullwhip effect generated and suffered by each level of a four-stage beer game supply chain when different demand scenarios are considered. The paper shows that the actors who generate lower bullwhip are those who suffer more from its effects. Moreover, a new definition of an inventory oscillations measure based on bullwhip definition is introduced. Finally the paper verifies that the new measure of inventory oscillations provides more information on supply chain performance than the bullwhip measure.     

An integrated approach to evaluating the production system in closed-loop supply chains

The increasing demands for environmental resource protection and sustainable development have been forcing enterprises to put sustainable supply chain management on their agendas in recent years. At the same time, intense global competition requires organisations to adopt practices that enable them to provide high-quality products and services. In this paper, we consider the problem of comprehensively evaluating the production system in closed-loop supply chains. We first propose an evaluation framework that consists of economic evaluation, product quality evaluation and ecological evaluation modules. Based on mathematical probability theory and the dynamic characteristics of reverse supply chain logistics, we then focus on the evolution dynamics in the quality evaluation dimension, where the concept of product quality, which builds on the reliability and the time-utility value of a product, is proposed. The basic production evaluation model is then extended to incorporate different sustainable procurement strategies, which take into consideration the trade-offs among cost, environment and quality. An outline and corresponding flow chart of corporate procurement strategy optimisation are provided which allow the proposed evaluation model to be implemented in computer-aided decision-making, further providing decision support for production system and supply chain management. Simulation and case studies are presented to promote a better understanding of the model approach and its managerial implications. Results also suggest that quality characteristics of components and sustainable procurement strategies are two important factors that determine the final production performance and should be paid special attention in closed-loop supply chain practice.     

供应链系统的动力学与复杂性研究问题综述

由于供应链的动态性和复杂性对系统性能的影响日趋明显,供应链系统的动力学和复杂性问题正在成为供应链设计、分析、优化和管理研究的一个热点。不同领域的学者一般仅关注供应链系统动力学和复杂性问题中的某些方面,而很少从更广泛的视角去观察分析这些问题及其相互联系。目前还没有就这些基本问题进行完整综述的文献报道。通过对该领域相关研究文献的分析和归纳,总结出供应链系统动力学和复杂性基本问题的框架内容,力图对供应链系统的动力学和复杂性有一个整体认识。     

A review of coordination studies in the context of supply chain dynamics

Supply chain management is and has been a popular research topic in recent years. Among the reported studies, coordination is an important ingredient to improve the performance of supply chains subject to the presence of system dynamics. This paper sets out to review some recent supply chain studies in the last decades that are related to coordination among supply chain members regarding supply chain dynamics. Focus is put on inventory management problems. More than a hundred research papers are reviewed and they are broadly categorised into analytical approaches and simulations approaches. They are further divided into sub-categorises. Observations of each category are summarised in this paper so that characteristics of each of which could be comprehended. In addition, the concluding section reveals some insights that could be considered for future research regarding coordination in supply chains and supply chain systems dynamics.     

From waste to value – a system dynamics model for strategic decision-making in closed-loop supply chains

Although the field of closed-loop supply chain management has attracted a lot of attention in recent years and the management of reverse logistics processes has become a major field of supply chain management, there is still a lack of research conducting analyses using a comprehensive approach that takes the complexity of problems of reverse logistics processes into account. Hence, the purpose of this paper is to develop a model that allows an original equipment manufacturer in the electronics industry to test different value recovery strategies for business-to-business products in a closed-loop supply chain setting. For this purpose system dynamics is used because this approach enables one to capture the high complexity of reverse logistics processes and is suitable, contrary to traditional optimisation approaches, for analysing the dynamic behaviour of closed-loop supply chains comprehensively. The simulation analysis identifies leverage points for the improvement of decisions concerning reverse logistics. In particular, the simulation runs conducted highlight the high complexity and connectivity inherited with various value recovery processes. The paper contributes to a better understanding of supply chain dynamics, the impact of product backflow, and reverse logistics.     

Risk assessment for the supply chain of fast fashion apparel industry: a system dynamics framework

With the rapid progress of science and technology and continuously growing customer expectations, share of merchandise exhibiting characteristics of perishability is on the rise and a wide range of industries are affected by this phenomenon. This paper focuses on the fast fashion apparel industry due to its particular characteristics such as short life cycle products, volatile demand, low predictability, high level of impulse purchase, high level of price competition and global sourcing. A system dynamics model is proposed for analysing the behaviour and relationships of the fast fashion apparel industry with three supply chain levels. The Conditional Value at Risk measure is applied to quantify the risks associated with the supply chain of these products and also to determine the expected value of the losses and their corresponding probabilities. Multiple business situations for effective strategic planning and decision-making are generated. In particular, the impact of lead time and delivery delays on the supply chain performance (inventory, cost, backlog and risk) is analysed as the key to success for this industry is to satisfy customers’ needs in the shortest time.     

Inventory Management of a Plant Spare Parts Supply Chain

In spare parts industries, firms are dealing with a situation which is more and more uncertain due to the supply chain structure and variable demands. This paper presents a Bayesian approach to forecast demand and subsequently determine the appropriate parameter S of an (S - 1; S) inventory system for controlling plant spare parts. We apply the Bayesian approach in an innovative way to specify the initial prior distributions of the failure rates, using the initial estimates and the failure history of similar items. According to the proposed method, a lower base stock than the one currently used is sufficient to achieve the desired service level.     

Coordination and performance analysis for a three-echelon supply chain with a revenue sharing contract

This paper focuses on a three-echelon supply chain composed of a manufacturer, a distributor and a retailer for a single selling period. Based on a revenue sharing contract, the coordination of the decentralised supply chain with the simultaneous move game or the leader–follower game is analysed. It is determined that the revenue sharing contract can coordinate the decentralised supply chain with the simultaneous move game. Our analysis reveals that the revenue sharing contract cannot coordinate the decentralised three-echelon supply chain with the leader–follower game except for a special situation. However, this result provides an opportunity to develop methodology and results that measure the potential improvement in supply chain performance that can be gained from utilising the revenue sharing contract. This is an important aspect of this paper.     

美国汽车业的供应链策略分析——互联网的影响

互联网的建立 ,实现了大量的信息流动 ,因而使供应链的本质起了极大的变化。汽车制造商为取得竞争优势 ,需要对其战略重新定位。为了得到更大的市场 ,公司必须做到以下两点 :一是缩短产品生产周期 ;二是缩短产品开发周期。为了降低成本 ,公司必须降低整条价值链中每一个环节的成本。商家通过互联网向顾客销售汽车及零部件 ,使得商家在配送和零售的模式上发生了很大的变化。这一变化不仅向公司提供了更好的市场透明度 ,更向消费者提供了直接挑选货品的机会。商家为顾客开启的大门还削减了传统销售中用于配送和零售的中介费用。本文的目的在于研究互联网中企业对企业的影响 ,以及今后应该如何置身于这一业务。供应商和汽车制造商应如何在互联网时代进行商业行为呢 ?本文的目的在于分析传统的 ,即以竞争和合作为特征的供应链关系的变化。我们将着眼于供应关系的改变、成本模式和样式转变等。本文结构如下 :第一节是对目前问题及其重要性的介绍 ;第二节主要讨论问题的一般表示形式 ,以及为取得战略竞争优势 ,解决问题的方法。第三节详细分析了汽车业的各个方面及其供应链。最后提出了企业的战略和结论。     

The value of nonlinear control theory in investigating the underlying dynamics and resilience of a grocery supply chain

In an empirical context, a method to use nonlinear control theory in the dynamic analysis of supply chain resilience is developed and tested. The method utilises block diagram development, transfer function formulation, describing function representation of nonlinearities and simulation. Using both ‘shock’ or step response and ‘filter’ or frequency response lenses, a system dynamics model is created to analyse the resilience performance of a distribution centre replenishment system at a large grocery retailer. Potential risks for the retailer’s resilience performance include the possibility of a mismatch between supply and demand, as well as serving the store inefficiently and causing on-shelf stock-outs. Thus, resilience is determined by investigating the dynamic behaviour of stock and shipment responses. The method allows insights into the nonlinear system control structures that would not be evident using simulation alone, including a better understanding of the influence of control parameters on dynamic behaviour, the identification of inventory offsets potentially leading to ‘drift’, the impact of nonlinearities on supply chain performance and the minimisation of simulation experiments.     

系统动力学的碳排放政策对供应链影响

随着低碳经济的发展,碳排放政策对于供应链的影响越来越受到关注。建立了基于系统动力学的单个供应商和销售商的供应链模型,并在此基础上引入强制排放和碳税两种碳排放政策。利用模型仿真,分析两种排放政策对于供应商、销售商及整个供应链的总成本和碳排放的影响。研究表明在强制排放模型中,不同的碳排放额度会使销售商选择不同的订货周期,发现合理的排放额度才能引导供应链双方降低排放,否则不仅达不到减排的目的,反而影响供应链效率;而在碳税模型中,提高碳税税率虽然会使政府获取一定的收益,但是实际上可能带来供应链总成本的上升和碳排放的增加,需要合理制定碳税税率引导绿色供应链发展。     

What is the role of value-added service in a remanufacturing closed-loop supply chain?

While the previous literature overlooks value-added service in a closed-loop supply chain (CLSC), we consider new research problems with embedding value-added service into remanufacturing models. In this paper, we mainly study the role of value-added service in a CLSC and investigate how the value-added service influences profits and other decision variables. Then, we evaluate the performance of the CLSC in different service structures, where a manufacturer or a retailer provide the value-added service. Systematic comparisons and numerical studies show that the supply chain is more effective when service is provided by a manufacturer rather than by a retailer. Also, value-added service improves the whole supply chain performance and plays a regulatory role in a CLSC and influences the decisions of supply chain members. We also show that while a service cost-sharing mechanism can only optimise rather than achieve the supply chain coordination, and the degree of optimisation depends on cost-sharing percentage, the two-part tariff contract can be an effective mechanism to coordinate decentralised service scenarios by generating the same supply chain performance in a centralised service architecture model.     

Risks and performance in supply chain: the push effect

A risk, when it occurs, causes negative effects on outputs. Typically risks are not independent, as multiple risks occur simultaneously. These risks have links, creating a ‘push’ effect, thus increasing the severity of each and all risk(s) on outputs. This paper aims to verify the mechanism of the push effect that is a new approach in the supply chain risk management literature. In this study, two models were compared: (1) only exists in direct effects of risks on supply chain performance, i.e. the competitive model. The other, (2), contains relationships among risks that show the mechanism of the push effect, i.e. the hypothesised model. Empirical evidence found in the Vietnam construction sector proved that the hypothesised model is better suited and has greater effect on supply chain performance in terms of each and all risk(s). Comparing 55% variance of the competitive model, the hypothesised one can explain up to 73% variance of supply chain performance. These results confirm our hypotheses of the push effect. Furthermore, findings achieved from this research can be used as ‘a guideline’ for reducing the impact of this mechanism.     

Joint decisions for R/M integrated supply chain using system dynamics methodology

In the remanufacturing/manufacturing (R/M) integrated supply chain, the decisions of the manufacturer, the wholesaler, the retailer, the parts producer, the raw materials supplier, the collector, and the disassembly centre are interactional. In this paper, a system dynamics model is proposed to examine the long-term behaviour of the R/M integrated supply chain with reuse, remanufacturing, and recycling. The optimal decision sets of the remanufacturing ratio and the setup period of remanufacturing (r) are given, the joint decisions of all members of R/M integrated supply chain under optimal r are presented by the simulation results, and the impacts of optimal r on the joint decisions are analysed.