基于马尔可夫分析的再制造系统生产策略比较

研究包含对废旧品回收和拆解的再制造系统的生产策略。在整个在制造系统中,包含一个拆解进程,该进程可以把回收的废旧品拆解,使之变成被处理的垃圾或者是可用于再制造的原材料及零部件。对于整个再制造系统,提出两种生产策略：1） 由系统尽力生产直至某一库存点库存达到饱和;2） 系统生产至某一库存点达到某一临界值时即停止生产。通过马尔可夫分析可对两种策略下的再制造系统的效率指标进行精确评价,最后运用数值试验对两种策略进行比较分析。     

Progress of remanufacturing engineering and future technology

After development for decades, abroad remanufacturing has formed a complete industrial system. At present, the research emphases are on marking logistics management and market cultivation theory of remanufacturing products, and so on. The Chinese remanufacturing starts fairly late. After 10 years of development, it formed a remanufacturing mode with Chinese characteristics that is sustained by high-tech industries, using the surface engineering
technology to restore the size and improve properties, and combining manufacturing, study and research together. The remanufacturing mode is not only circular but also economic. With the development of science and technology, future remanufacturing technology will break the previous limits, explore and understand the limits of micro machining. It will carry out the waste product remanufacturing in the micro-nano scale, and extend the remanufacturing industry to a more broad space.     

The Integration Model of Closed-Loop Supply Chain Resource Allocation Considering Remanufacturing

Logistics resource planning is an integration model of materials requirement planning and distribution resource planning which is a resource allocation technology. It is a technology of satisfying both production material supply and resource allocation optimization which is based on inventory management. For the remanufacturing supply chain, recycling and rebuilding of products form a reverse materials movement loop which challenges the traditional logistics resource planning system. For the characteristics of reverse logistics of remanufacturing supply chain, we propose a closed-loop supply chain resource allocation model based on autonomous multi-entity. We focus on integration resource allocation model of materials requirement planning and distribution resource planning considering remanufacturing.     

Dynamic product acquisition in closed loop supply chains

We consider a closed-loop supply chain where demand can either be satisfied by manufacturing new products or by buying back used products from customers and upgrading their functionality by remanufacturing. A joint buy-back pricing and manufacturing–remanufacturing decision model at the operations–marketing interface is presented that allows for dynamic parameters, e.g. product life cycles and seasonal aspects. The model allows the identification of beneficial opportunities for buying back and storing used products for immediate and future recovery. We present a new deterministic, dynamic, continuous-time optimisation model, derive necessary and sufficient optimality conditions, and develop a solution algorithm to find the cost-minimising manufacturing and remanufacturing policies as well as buy-back strategies for used products based on Pontryagin's Maximum Principle. It is shown that, in general, an optimal policy will include time intervals where returns are acquired so as to synchronise demand and remanufacturing, where returns are acquired and stored for future remanufacturing, and intervals where demand is satisfied by a mix of manufactured and remanufactured products. Furthermore, we discuss several reactive and proactive acquisition and remanufacturing heuristics and show under which conditions they are optimal. The findings are illustrated by numerical examples.     

Dynamic disassembly planning for remanufacturing of multiple types of products

With the increased need for remanufacturing of end-of-life products, achieving economic efficiency in remanufacturing is urgently needed. The purpose of this study was to devise a cost-minimisation plan for disassembly and remanufacturing of end-of-life products returned by consumers. A returned end-of-life product is disassembled into remanufacturable parts, which are supposed to be used for new products after being remanufactured. Each end-of-life product is disassembled into parts at variable levels and through variable sequences as needed, taking into account not only disassembly but also manufacturing, remanufacturing, and holding inventory of remanufacturable parts. This study proposes a mixed integer linear programming (MILP) model for derivation of the optimal disassembly plan for each returned product, under deterministically known demand and return flows. For the purposes of an illustrative example, the proposed model was applied to the formulation of an optimal disassembly and remanufacturing plan of ‘fuser assembly’ of laser printers. The solution reveals that variable-level disassembly of products saves a significant remanufacturing cost compared with full disassembly.     

Green Remanufacturing Engineering and Its Development Strategy in China

Made in China 2025 proposes that “develop the remanufacturing industry vigorously, implement high-end remanufacturing, smart remanufacturing, and in-service remanufacturing, advance the identification of remanufacturing products, and promote sustainable and healthy development of the manufacturing industry”. Remanufacturing is an extension of the manufacturing industry chain, and it is an important part of advanced manufacturing and green manufacturing. The product function, technical performance, greenness and economy of the remanufacturing products are no worse than those of the new products. The cost of remanufacturing products is only about 50% of new products. Remanufacturing can save energy 60%, and material 70%, so the adverse impact on the environment is significantly reduced. At present, China’s remanufacturing industry is developing rapidly, and the manufacturing pilot has been in full swing. Meanwhile, the policies and regulations, basic theory, key technology, and industry standards of remanufacturing have been continuously innovated and completed.     

Product structure complexity and scheduling of operations in recoverable manufacturing

Recoverable manufacturing is becoming an increasingly important alternative to firms as they develop environmentally sound strategies aimed at minimizing waste and resources. Remanufacturing helps minimize costs and conserve resources through methods such as extending product life cycles via refurbishments and technical upgrades which require the use of only a fraction of the resources and energy associated with a new product. In this study the impact of product structure complexity on other managerial operating decisions is examined in a remanufacturing environment. It is shown that in the remanufacturing environment, with its greater inherent uncertainty, product structure complexity significantly affects the choice of scheduling policies used. Recommendations as to the scheduling policy to use for a dominant product structure in a given environment are made.     

Planning stability in a product recovery system

Recovery of used products is an issue of growing importance due to customer expectations and environmental regulation. As a consequence, companies need to adapt their material management taking into account inbound flows of used products. Corresponding inventory control models have been proposed in literature. In this paper we address the issue of planning stability in a product recovery context. To this end, we consider rolling horizon planning for a stock point facing stochastic demand and product returns. We analyze the impact of the return flow on planning stability and compare the system behaviour with a traditional production environment. We show that structural results derived for traditional inventory models remain valid in a product recovery context. Moreover we discuss counterintuitive effects resulting from interaction between planning stability and stock levels.     

The effect of categorizing returned products in remanufacturing

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.     

Bullwhip and inventory variance in a closed loop supply chain

A simple dynamic model of a hybrid manufacturing/remanufacturing system is investigated. In particular we study an infinite horizon, continuous time, APIOBPCS (Automatic Pipeline Inventory and Order Based Production Control System) model. We use Åström’s method to quantify variance ratios in the closed loop supply chain. Specifically we highlight the effect of a combined “in-use” and remanufacturing lead-time and the return rate on the inventory variance and bullwhip produced by the ordering policy. Our results clearly show that a larger return rate leads to less bullwhip and less inventory variance in the plant producing new components. Thus returns can be used to absorb demand fluctuations to some extent. Longer remanufacturing and “in-use” lead-times have less impact at reducing inventory variance and bullwhip than shorter lead-times. We find that, within our specified system, that inventory variance and bullwhip is always less in supply chains with returns than supply chains without returns. We conclude by separating out the remanufacturing lead-time from the “in-use” lead-time and investigating its impact on our findings. We find that short remanufacturing lead-times do not qualitatively change our results.     

Environmental issue in an integrated production and maintenance control of unreliable manufacturing/remanufacturing systems

This paper addresses a joint production and maintenance problem under environmental constraints and reliability issues in a manufacturing/remanufacturing context. The manufacturing system is composed of one machine producing one type of product. The remanufacturing system, also composed of one machine, retrieves returned products from the market in order to refurbish them. The manufacturing and remanufacturing systems aim to satisfy random demands under a given service level. Moreover, the entire system generates harmful emissions. Exceeding carbon emission limits defined by authorities may risk sanctions. We aim to propose a compromise between ecologic and economic production and maintenance plan by calling on green subcontracting in order to satisfy the demand and avoid emission excess. Three models are proposed in this paper. These models tackle mainly the basic production problems and propose alternative equivalent solution schemas for future extensions. The robustness and usefulness of the proposals are illustrated with various examples and sensitivity analyses.     

Optimal policies in hybrid manufacturing/remanufacturing systems with random price-sensitive product returns

We study a production planning problem in which a manufacturer aims to meet a random market demand by manufacturing new product and remanufacturing returned product. The product returns are random and price-sensitive. To maximise his profit, the manufacturer needs to optimally decide on the acquisition price for the returned product as well as the quantities of the new product to be manufactured and the returned product to be remanufactured. We investigate two cases based on the relative lengths of the manufacturing and remanufacturing lead times. (1) In the case with a shorter manufacturing lead time, the manufacturer first decides his acquisition price for the returned product before the production starts, and then decides the quantities of manufacturing/remanufacturing after the product returns are realised. (2) In the case with a shorter remanufacturing lead time, the manufacturer first decides the manufacturing quantity and the acquisition price simultaneously, and then the remanufacturing quantity based on the quantity of manufactured and returned products. Each case is formulated as a two-stage stochastic optimisation problem, and the corresponding optimal polices of both are characterised and derived.     

A study of the optimal production strategy for hybrid production systems

Due to increased environmental awareness, the issue of recycling and disassembling damaged or malfunctioning products after consumption to obtain useable parts for remanufacturing has become essential. This study considers a hybrid production system with both external and internal reverse logistics in which the external recycled products are utilised for remanufacturing to satisfy demand first, and then the ordinary manufacturing process may supplement this if there is any shortage in production. In addition, the defective items produced internally by either the manufacturing or the remanufacturing process can also be repaired by a remediation process. The objective of this study is to determine the optimal strategy for the manufacturing, remanufacturing, disposal, and remediation rates. Three conditions are considered in which the production strategy varies with different yield rates and capacity limits. The impacts of related factors on the production strategy are investigated to probe the trade-offs between product consumption and environmental protection.     

The integral decision on production/remanufacturing technology and investment time in product recovery

This paper examines the financial impact of technological decisions firms face when introducing a new product which, as firms increasingly assign responsibility for the recovery of their used products, must be expanded to include their influence on available options on how to deal with used products. The integrated choice between a low (disposal) or high (remanufacturing) level of product recovery and, in the second case, at which time to start remanufacturing activities and whether the firm would dispose of initial product returns or store them until start time result in three generic options: (a) design for single use, (b) design for reuse, and (c) design for reuse with stock-keeping. After introducing a basic dynamic framework consisting of a product life cycle for the demand and a similar development for an external return stream, the Net Present Values of the relevant payments connected with each option are given and optimal policies for options (b) and (c) are derived. An extensive numerical study is used to examine the potential benefits from using the inventory and the applicability of simple heuristic rules for stock-keeping and for determining when to start remanufacturing.     

Application of interpretive structural modelling for analysis of factors influencing lean remanufacturing practices

The contemporary manufacturing scenario witnesses the adoption of lean remanufacturing concepts in a concerted manner. Lean remanufacturing is a newly evolved manufacturing process concerned with manufacturing and remanufacturing of products to effectively utilise available energy and resources, while reducing wastes in the process and thereby increasing efficiency. The advantages include process streamlining coupled with end-of-life decisions. A structural model needs to be developed to clarify the interrelationships among factors influencing lean remanufacturing practices. In this study, interpretive structural modelling method has been used to develop the structural model depicting interrelationships and most dominant and least dominant factors. Twenty factors are being identified based on expert opinion from 35 Indian automotive component remanufacturing organisations. The identified most dominant factors include a strong top management commitment with proper strategy selection, long-term vision and participation and a strong understanding of the current product and process designs. MICMAC analysis has been conducted to categorise the factors. The inferences based on the study have been derived. The novel aspect of this study is that it presents the development of structural model to identify the most dominant factors influencing the implementation of lean remanufacturing principles.     

Reverse Logistics: a stochastic EOQ-based inventory control model for mixed manufacturing/remanufacturing systems with return policies

This paper focuses on mixed manufacturing/remanufacturing systems, where manufacturing or purchase of new items integrates product reuse or remanufacturing, with the purpose to achieve a complete and timely demand satisfaction. We formulate a stochastic Economic Order Quantity (EOQ)-based inventory control model for a mixed manufacturing/remanufacturing system. The model is intended to identify the need of placing a manufacturing/purchasing order, to avoid the occurrence of stock-out situations. We then formulate a total cost minimisation problem, to derive the optimal return policy, this latter being a financial incentive paid to customers to increase the flow of returned items. The model developed is investigated through simulations, in order to assess the effect of stochasticity (of demand, return fraction and return delay) on the optimal return policy of the system; then, it is validated through a case study, to derive indications concerning its practical application in real cases. Our study ultimately provides a framework for practitioners to establish EOQ policies in reverse logistics contexts and to evaluate the opportunity of establishing a return policy in those contexts.     

Hybrid (re)manufacturing: manufacturing and operational implications

Remanufacturing presents an option to recover value from used products. However, hybrid (re)manufacturing (i.e. simultaneous manufacturing and remanufacturing) is a challenge, owing to non-uniform availability and heterogeneous quality of returns. In this paper, we examine how heterogeneous quality and non-uniform quantity of returns influence the optimal production rates and inventory levels in a hybrid (re)manufacturing system that incurs costs to readjust manufacturing and remanufacturing capacities on a temporary basis. Specifically, we propose a mixed integer linear programming (MILP) based approach to obtain the optimal production plan for a specified planning horizon. We apply the proposed model to the (representative) operational data of an office equipment manufacturer to evaluate the impacts of quality of returns, quality-based segregation of returns, and capacity readjustment costs. The study provides insights into the effects of trade-offs among different operational costs in a hybrid (re)manufacturing system.     

Product acquisition management: Current industry practice and a proposed framework

Remanufacturing requires that used products (cores) be obtained from the enduser at the end of their current life cycle so that the value-added may be recovered and the products returned to functional use again. The acquisition of cores to be remanufactured in such recoverable manufacturing systems is a complex set of activities that requires careful coordination to avoid the uncontrolled accumulation of core inventory, or unacceptable levels of customer service. The authors report on current industry practice via an extensive survey of North American remanufacturing firms. The authors propose a formal framework for Product Acquisition Management (PrAM) to coordinate, monitor, and provide an interface between reverse logistics and production planning and control activities. Finally, a series of managerial guidelines for the organization of PrAM activities is proposed. We conclude that managers should take actions that consistently reduce the variance inherent in a remanufacturing environment.     

Application of analytical network process for analysis of product design characteristics of lean remanufacturing system: a case study

The modern manufacturing systems are adopting with lean practices to ensure value addition and waste elimination. Also, product recovery options are found to be vital. Appropriate product design characteristics are identified, and their prioritization is framed as decision-making problem with multiple criteria. Analytical network process is used as solution methodology. The objective of the study is to formulate multi-criteria decision making problem for assessment of lean remanufacturing product design characteristics. The priority order of lean remanufacturing operations is obtained. The study is exemplified with a case conducted with reference to remanufacture of an automotive component. The priority order of criteria is Disassembly > Cleaning > Inspection > Remanufacturing > Reassembly. The inferences desired from the study would facilitate cleaner manufacturing practices. Sensitivity analysis is conducted and practical validity of the method has been tested with an industrial case study.     

A robust optimisation model for hybrid remanufacturing and manufacturing systems under uncertain return quality and market demand

In remanufacturing research, most researchers predominantly emphasised on the recovery of whole product (core) rather than at the component level due to its complexity. In contrast, this paper addresses the challenges to focus on remanufacturing through component recovery, so as to solve production planning problems of hybrid remanufacturing and manufacturing systems. To deal with the uncertainties of quality and quantity of product returns, the processing time of remanufacturing, remanufacturing costs, as well as market demands, a robust optimisation model was developed in this research and a case study was used to evaluate its effectiveness and efficiency. To strengthen this research, a sensitivity analysis of the uncertain parameters and the original equipment manufacturer’s (OEM’s) pricing strategy was also conducted. The research finding shows that the market demand volatility leads to a significant increase in the under fulfilment and a reduction in OEM’s profit. On the other hand, recovery cost reduction, as endogenous cost saving, encourages the OEM to produce more remanufactured products with the increase in market demand. Furthermore, the OEM may risk profit loss if they raise the price of new products, and inversely, they could gain more if the price of remanufactured products is raised.