Showing papers on "Remanufacturing published in 2004"

Closed-Loop Supply Chain Models with Product Remanufacturing

Abstract: The importance of remanufacturing used products into new ones has been widely recognized in the literature and in practice. In this paper, we address the problem of choosing the appropriate reverse channel structure for the collection of used products from customers. Specifically, we consider a manufacturer who has three options for collecting such products: (1) she can collect them herself directly from the customers, (2) she can provide suitable incentives to an existing retailer (who already has a distribution channel) to induce the collection, or (3) she can subcontract the collection activity to a third party. Based on our observations in the industry, we model the three options described above as decentralized decision-making systems with the manufacturer being the Stackelberg leader. When considering decentralized channels, we find that ceteris paribus, the agent, who is closer to the customer (i.e., the retailer), is the most effective undertaker of product collection activity for the manufacturer. In addition, we show that simple coordination mechanisms can be designed such that the collection effort of the retailer and the supply chain profits are attained at the same level as in a centrally coordinated system.

Product and Process Design for Successful Remanufacturing

Abstract: Remanufacturing is an industrial process where used products are restored to useful life. This dissertation describes how products can be designed to facilitate the remanufacturing process. It also ...

Meeting the Closed-Loop Challenge: The Case of Remanufacturing

Abstract: This article examines the experiences of a major European car manufacturer in developing a dedicated car engine remanufacturing operation and a reverse logistics operation to support it. The company's efforts demonstrate that achieving reverse logistics flows through existing logistics channels is feasible and can prove relatively unproblematic. The real challenges involved in closing the loop were in managing the remanufacturing process in the face of external competition for old engines, internal competition for spare parts, and a lack of consideration from new engine designers. The case provides general lessons for successful remanufacturing and shows the importance of including reverse logistics and remanufacturing operations in an integrated approach to product management.

The effect of categorizing returned products in remanufacturing

Abstract: An increasing number of companies have been implementing comprehensive recycling and remanufacturing programs. These endeavors typically involve the operation of joint manufacturing and remanufacturing systems. One of the major challenges in managing such hybrid systems is the stochastic nature of product returns. In particular, there is significant variability in the condition of the returns. This paper presents an approach for assessing the impact of quality-based categorization of returned products. Through extensive numerical studies on a continuous-time Markov chain model, we show that incorporation of returned product quality in the remanufacturing and disposal decisions can lead to significant cost savings. We find that these savings are amplified as the return quality decreases, and as the return rate increases. We also show that prioritizing higher quality returns in remanufacturing is, in general, a better strategy.

Supply-chain network configuration for product recovery

Abstract: The current growth in consumption results in resource reduction, increasing waste production and, ultimately, environmental deterioration. Both government and consumer concerns regarding these issues have been driving reduction efforts in waste and natural resource-usage. These environmental issues, in addition to economic opportunities, result in the concept of product cycles that oppose the traditional ‘one-way’ economy. One approach is to create product recovery networks in which used products are collected, reprocessed and later redistributed to the customer. Product recovery networks differ from typical forward-only networks. Therefore, specific work considering their issues is necessary. In this work, we study a closed-loop supply chain in which manufacturers produce new products and remanufacture used products. The decisions to be made are: which warehouses and collection centres should be open, which warehouses should have sorting capabilities and how much material should be transported between ea...

Value of information in remanufacturing complex products

Abstract: Remanufacturing facilities usually face a trade-off between limited information about remanufacturing yields and potentially long supplier lead times. To improve production performance, these firms may attempt to acquire more timely and accurate information about remanufacturing yields or alternatively, to reduce the lead times of purchased parts. We develop four decision-making models to evaluate the impact of yield information and supplier lead time on manufacturing costs. We identify the operating conditions under which these capabilities are valuable, along with their relative impact on facility performance. Each model is formulated as an infinite horizon, stochastic dynamic program (Markov decision process). Our results indicate that the yield information is generally quite valuable, while investments in supplier responsiveness provide trivial returns to products with few parts. However, as product complexity increases with large number of target parts, the value of short lead times increases.

Simple heuristics for push and pull remanufacturing policies

Abstract: Inventory policies for joint remanufacturing and manufacturing have recently received much attention. Most eorts, though, were related to (optimal) policy structures and numerical optimization, rather than closed form expressions for calculating near optimal policy parameters. The focus of this paper is on the latter. We analyze an inventory system with unit product returns and demands where remanufacturing is the cheaper alternative for manufacturing. Manufacturing is also needed, however, since there are less returns than demands. The cost structure consists of setup costs, holding costs, and backorder costs. Manufacturing and remanufacturing orders have non-zero lead times. To control the system we use certain extensions of the familiar (s,Q) policy, called push and pull remanufacturing policies. For all policies we present simple, closed form formulae for approximating the optimal policy parameters under a cost minimization objective. In an extensive numerical study we show that the proposed formulae lead to near-optimal policy parameters.

Remanufacturing: a key strategy for sustainable development

Abstract: Remanufacturing is a process of bringing used products to "like-new" functional state with warranty to match. It recovers a substantial proportion of the resource incorporated in a used product in its first manufacture, at low additional cost, thus reducing the price of the resulting product. The key remanufacturing problem is the ambiguity in its definition leading to paucity of knowledge and research in the process. Also, few remanufacturing tools and techniques have been developed to improve its efficiency and effectiveness. This paper addresses these issues by describing the findings of in-depth UK case studies, including, a robust remanufacturing definition and an analytic model of the generic remanufacturing business process for improving remanufacturing knowledge and expertise.

The impact of information transparency on the dynamic behaviour of a hybrid manufacturing/remanufacturing system

Abstract: A combined manufacturing/remanufacturing system is modelled and its dynamic behaviour is investigated using a control engineering approach. The model is an extension of the automated pipeline, inventory and order based production control system (APIOBPCS), which is well understood from a dynamic perspective. It is assumed that the remanufacturing process is based on a PUSH policy. Utilising different levels of information transparency from the remanufacturing process, three system types are developed and compared. Mathematical and simulation analyses of the system types were undertaken and their robustness to remanufacturing process uncertainties were tested. Our analysis indicates that the greater the degree of information transparency, the greater the robustness of the hybrid system.

Optimal control of a remanufacturing system

Abstract: An optimal control problem of a remanufacturing system under stochastic demand is studied. The system is formulated by a Markov decision process, which is a class of stochastic sequential processes in which the reward and transition probability depend only on the current state of the system and the current action. The models have gained recognition in such diverse fields as engineering, economics, communications, etc. Each model consists of states, actions, rewards and transition probabilities. The paper considers two types of inventories: the actual product inventory in a factory and the virtual inventory used by a customer. The state of the remanufacturing system is defined by both inventory levels. One can obtain the optimal production policy that minimizes the expected average cost per period. The paper also considers some scenarios under various conditions and shows the example of controlling the remanufacturing system.

Disassembly sequencing problem: a case study of a cell phone

Abstract: Selection of an optimal disassembly sequence is essential for the efficient processing of a product at the end of its life. Disassembly sequences are listings of disassembly actions (such as the separation of an assembly into two or more subassemblies, or removing one or more connections between components). Disassembly takes place in remanufacturing, recycling, and disposal with a disassembly line being the best choice for automation. In this paper, the disassembly sequencing problem is solved for a cell phone case on a disassembly line, seeking a sequence which is feasible, minimizes the number of workstations (and hence idle times), provides for early removal of high demand/value parts, provides the removal of parts that lead to the access of greatest number of still-installed parts, and early removal of hazardous parts as well as for the grouping of parts for removal having identical part removal directions. Since finding the optimal sequence is computationally intensive due to factorial growth, a heuristic method is used taking into account various disassembly-specific matters. Using the experimentally determined precedence relationships and task times of a real-world cell phone, a MATLAB program is designed and a sequencing solution is generated. Finally, Design for Disassembly (DFD) improvements are recommended with respect to environmentally conscious manufacturing.

Inventory strategies for systems with fast remanufacturing

Abstract: We describe hybrid manufacturing/remanufacturing systems with a long lead time for manufacturing and a short lead time for remanufacturing. We review the classes of inventory strategies for hybrid systems in the literature. These are all based on equal lead times. For systems with slow manufacturing and fast remanufacturing, we propose a new class. An extensive numerical experiment shows that the optimal strategy in the new class almost always performs better and often much better than the optimal strategies in all other classes.

Economic evaluation of disassembly processes in remanufacturing systems

Abstract: A model to deal with the disassembly processes in remanufacturing systems is presented with focus being on evaluating their economic consequences. More specifically, the model assists decisions suc ...

Coordination in Closed-Loop Supply Chains

Abstract: In any type of supply process, closed-loop or open-loop (Chapter 2), multiple decision-makers within a firm or in different firms are involved in decisions concerning the efficiency and the profitability of the supply process. For example, for consumer goods such as one-time use cameras (Kodak), the distributor network operates as the product return point due to the disposal convenience for the consumer. Kodak collects cameras from large retailers who also develop film for customers. The retailers are reimbursed both on a fixed-fee-per-unit basis and for transportation costs. Decision-makers in different companies control the return flow of cameras to the remanufacturing facility. Return flows of products can also be influenced by different decision-makers within a single firm. One example is tire retreading, a common recovery process for tires. When the tread of a tire is worn, the tire can no longer be used but the casing is often in good shape. Retreading is the process of replacing the worn tread by a new tread and reusing the casing. Typically, the demand of retreaded tires depends on the price discount that is given with respect to new tires. The supply of retreadable tires, however, depends on the technology chosen by the tire manufacturer. Hence, technology decisions made by the product design department, and marketing decisions made by the marketing department, determine the flows of retreaded tires.

Production planning for product recovery management

Abstract: Production Planning and Control (PPC) in product recovery systems faces complications due to several characteristics which typically require tools different from, and in addition to, those known from traditional forward production and logistics systems (e.g., see Guide, 2000, and Inderfurth and Teunter, 2002). Many of these characteristics are due to additional specific operations necessary for disassembling, reprocessing, and rearranging recoverable products. Furthermore, in product recovery management, considerable sources of uncertainty have to be taken into consideration concerning the arrival of recoverables as well as the outcome of disassembly and reprocessing activities. The specific environment that poses challenges for PPC under product recovery will be demonstrated by two case examples, one of them concerning remanufacturing of used products in the field of discrete products’ manufacture, and the other considering rework of by-products in the field of process industries.

Managing dynamic product recovery: an optimal control perspective

Abstract: In the previous chapters, the impact of the presence of product returns on batching and safety inventory considerations has been addressed under stationary conditions. In this chapter, we will focus on a different aspect, namely the impact of dynamic phenomena. Whereas the insights provided by Chapters 7, 8, and 10 mainly help to improve operational decisions, the benefit of the dynamic optimal control framework lies in the assistance of operational as well as strategic/tactical decisions like competitive strategy, selection of recovery processes, investments in remanufacturing technology, product life cycle decisions, production planning under seasonal demand, etc. As a consequence of reducing model complexity, we will restrict the analysis to deterministic but time varying environments. These dynamic conditions are present in most practical applications, and in the following we will briefly illustrate this aspect using DaimlerChrysler’s engine recovery operations (see Driesch et al., 1997).

Reverse logistics: a study of bullwhip in continuous time

Abstract: A simple dynamic model of a hybrid manufacturing/remanufacturing system is developed. In particular the model is used to study an infinite horizon, continuous time, APIOBPCS (automatic pipeline inventory and order based production control system) model. We specifically highlight the effect of remanufacturing lead-time and the return rate on the bullwhip produced by the ordering policy. Our results clearly show that a larger return rate leads to less bullwhip, thus returns can be used to absorb demand fluctuations to some extent. Longer remanufacturing lead-times have less impact at reducing bullwhip than shorter lead-times. We conclude, within our specified system, that bullwhip is always less with returns than without returns.

Systematic approach to the planning and execution of product remanufacture

Abstract: The challenge of remanufacturing is the production of quality products from returned discarded cores of unknown quality. Case studies and published literature reveal that there are no established processes tailored to the particular needs of product remanufacture. This paper outlines the difficulties associated with the planning and execution of product remanufacture. It then presents a systematic approach for the planning and execution of product remanufacture based upon the failure mode and effect analysis (FMEA) method. The approach is demonstrated in case studies of the remanufacture of an air-conditioning unit and a turbocharger. The results from the case studies are discussed and conclusions are drawn. The wider issues associated with remanufacturing including reliability and safety, further research opportunities and the design of functional products are then discussed and conclusions drawn.

Opportunities for remanufactured electronic products from developing countries: hypotheses to characterise the perspectives of a global remanufacturing industry

Abstract: Global legislative and market pressures are increasingly enforcing the concept of product life cycle management (LCM), or product stewardship, particularly in the electronics sector. Thereby, from an environmental perspective, end-of-life regulations and obligations require the technology managers of original equipment manufacturers (OEMs) in developed countries to consider remanufacturing and reuse as an attractive economic alternative to expensive recycling and the final disposal of electronic products. Furthermore, developing countries offer an expanding market for affordable quality spare parts, especially for the repair of cellular phones and household appliances. These dissimilar markets could be complementary from the perspective of the remanufacturing sector. Additional requirements of this relatively informal sector in developing countries must be considered, specifically product cleaning processes and test routines that may necessitate the transfer of technologies. Also, training and formalisation are needed to deliver quality services in the repair sector of developing countries. Potential market niches may also exist for inexpensive products from a formalised remanufacturing industry. Therefore, by moving from international isolation to global integration, remanufacturing and repair will profit from networking and synergy efforts in four arenas of the electronic product life cycle chain: market participants, products and applications, neighbouring technologies, and international regions.

On the complexity of the economic lot-sizing problem with remanufacturing options

Abstract: textIn this paper we investigate the complexity of the economic lot-sizing problem with remanufacturing (ELSR) options. Whereas in the classical economic lot-sizing problem demand can only be satisfied by production, in the ELSR problem demand can also be satisfied by remanufacturing returned items. Although the ELSR problem can be solved efficiently for some special cases, we show that the problem is NP-hard in general, even under stationary cost parameters.

Scheduling selective disassembly for plastics recovery in an electronics recycling center

Abstract: High-value engineering plastics demand in the electronics industry reaches nearly 1.5 million tons annually. Since these plastics are derived from nonrenewable petroleum-based resources, research for scheduling of plastics-to-plastics recycling is warranted. Recent research has shown the feasibility of extending the reverse electronics supply chain, driven primarily by remanufacturing and metals recovery, to include plastics recovery. The extended recycling process adds plastic cover disassembly for separation of the majority of the plastics in electronics prior to bulk processes for metals separation. In anticipation of recovered plastics demand for product housings, we develop scheduling rules for plastics demand-driven disassembly processes and test them in a discrete event simulation model of a recycling center. In our experimental design, we vary disassembly scheduling rules, the mix of end-of-life electronic product arrivals, and plastics demand. Although the mix of incoming products has a significant impact on plastics recovery rate, our results demonstrate that the application of plastics demand-driven or supply-based disassembly scheduling rules perform similarly in maintaining metals and plastics throughput from consumer electronics.

Mathematical model of reusability

Abstract: Recently the reuse of products or their components has been recognized as an effective way to reduce solid waste and to conserve natural resources. To decide whether a product or its component should be reused or not, we need to evaluate its reusability adequately. In this paper, as a criterion for the evaluation, the authors define and model the reusabilities of a product and its component, based on reliability theory. The authors define the reusability of a component as a probability that a product having been used for a time period ends its life but a component included in it is reusable. Based on the definition, the authors develop a mathematical model of reusability, which is a function of use time. The authors made several graphs of the mathematical model, with changing values for parameters such as shape parameter of the Weibull distribution. As a result, it is found that the reusability of a component does not always decrease as the use time is lengthened. This is interesting because it goes against the general impression that the reusability decreases as the use time is lengthened. Next, the authors define and model the reusabilities of a product and a unit. The authors believe that the models of reusabilities are useful for deciding whether a product or its component should be reused or not and the models may be used for production management for reuse and remanufacturing.

Modelling and controlling uncertainty in optimal disassembly planning through reinforcement learning

Abstract: Currently there is increasing consensus that one of the main issues differentiating the remanufacturing from the more traditional manufacturing processes is the need to effectively model and manage the high levels of uncertainty inherent in these new processes. The work presented in this paper formally establishes that the theory of reinforcement learning, one of the most actively researched areas in computational learning theory, constitutes a rigorous, effectively implementable modelling framework for providing (near) optimal solutions to the optimal disassembly planning (ODP) problem, one of the key problems to be addressed by remanufacturing processes, in the face of the aforementioned uncertainties. The developed results are exemplified and validated by application on a case study borrowed from the relevant literature.

Product take-back: sensors-based approach

Abstract: The driving forces behind product take-back and green manufacturing are well established The two main product end-of-life options are reuse/remanufacturing and recycling For either option, all take-back units are treated equally because no information that tracks the conditions of a product during its useful life is available For example, all expired PCs are treated equally; no distinction can be made about which units still have healthy hard disks This paper discusses sensor-based monitoring and prognostic methodologies for tracking the condition of products while being used by customers and timely and targeted servicing, smart and selective disassembling and refurbishing of products with known (long) remaining lives The paper also discusses the added benefits to product manufacturers when the time comes to redesign their products The real-time field data on service and utilization of products are communicated to manufacturers’ headquarters for further analysis

Benefit analysis and Surface Engineering Application of Automobile Engine Remanufacturing

Abstract: The statistic analysis of 3 000 STYLE modl engines showed that among the engines parts, about 23.7 % in quantity, 14.4 % in weight and 12.3 % in value could be directly reused. Meanwhile, after remanufacturing about 62 % in quantity, 80.1 % in weight and 77.8 % in value could be reused. That means, remanufacturing of old engines had excellent economic benefits. Suppose ten thousands engines could be remanufactured per year, the following benefits would be obtained: reclaiming additional values of 3.59 hundreds millions Yuan RMB, saving metallic materials 8.5 thousands tons, creating profits and taxes of 0.36 hundreds millions Yuan RMB, saving energy of 16 millions kilowatt-hours, reducing emission of CO2 about 13~17 thousands tons, and providing employment for 330 persons. By using surface engineering techniques, about 62 % waste parts in old engines could be repaired, and the quality of remanufactured engines became superior to the original products. The applications of advanced surface engineering techniques in engine remanufacturing have enhanced the availability of waste products, reduced the remanufacturing costs and made contributions to materials- and energy-saving and environment protection.