闭环供应链下再制造生产计划研究述评

再制造是实现循环经济"减量化、再利用、资源化"三原则的重要途径。再制造生产活动中,计划扮演着重要的先行角色。本文根据再制造系统的回收和拆卸特色,先讨论与再制造生产计划有关的几个重要参数;然后从再制造生产计划的结构层次入手,对再制造生产计划领域的研究进展进行探析;最后指出目前研究不足之处以及未来研究的可能方向。     

Rough-cut capacity planning for remanufacturing firms

Capacity planning is a critical element of any successful production planning and control system. A method of rough-cut capacity planning is developed, based on the bill-of-resources approach, that can be used to plan for capacity required for firms in a remanufacturing including overhaul repair operations environment. The modified bill-of-resources approach developed takes into account two major stochastic elements inherent in this environment; probabilistic material replacement factors and probabilistic routing files. A detailed example from an actual repair overhaul operation is presented to illustrate the technique.     

Production planning and control for remanufacturing: exploring characteristics and difficulties with case studies

Production planning and control for remanufacturing is a major managerial challenge in the operations management. Researches demonstrate the need for decision-making methods in this context, which has generated theoretical and quantitative studies. However, this area still lacks empirical studies dealing with the practical, day-to-day difficulties of remanufacturers. The purpose of this paper is to link the literature and practice in a systematic in such a way that it is possible to show the similarities and differences between theoretically listed needs and real cases, thereby extending the results of previous research. For this purpose, four case studies are considered. The cases involve original equipment manufacturers (OEM) of automotive parts that have remanufacturing operations. The results indicate that these companies have difficulties that have not been addressed to date in the literature related to the uncertainties inherent in remanufacturing. In addition, we find that these companies use simplified decision-making approaches.     

A robust optimization model for stochastic aggregate production planning

The aggregate production planning (APP) problem considers the medium-term production loading plans subject to certain restrictions such as production capacity and workforce level. It is not uncommon for management to often encounter uncertainty and noisy data, in which the variables or parameters are stochastic. In this paper, a robust optimization model is developed to solve the aggregate production planning problems in an environment of uncertainty in which the production cost, labour cost, inventory cost, and hiring and layoff cost are minimized. By adjusting penalty parameters, decision-makers can determine an optimal medium-term production strategy including production loading plan and workforce level while considering different economic growth scenarios. Numerical results demonstrate the robustness and effectiveness of the proposed model. The proposed model is realistic for dealing with uncertain economic conditions. The analysis of the tradeoff between solution robustness and model robustness is also presented.     

基于改进策略的混合型制造/再制造系统分析

在制造和再制造并存的混合型系统中,制造商需要同时协调新产品生产过程和旧产品再制造过程,这种双向物流的集成运作使得传统的生产规划和库存管理方式不再适用,如何构建一种有效的控制策略来协调生产过程和再制造过程就显得十分关键。本文在优化库存信息的基础上提出了一种适用于混合系统的改进策略,同时考虑到系统复杂性,主要采用控制理论中的传递函数技术构建了系统模型。仿真结果表明,本文提出的改进策略不仅可以有效协调新产品生产过程和旧产品再制造过程,而且还可以显著改善系统性能。     

Development and analysis of mathematical and simulation models of decision-making tools for remanufacturing

This article presents decision-making tools for remanufacturing. The first decision-making tool was used to address inventory lot-sizing problems in a hybrid remanufacturing–manufacturing system with varying remanufacturing fraction. In this article, the new inventory lot-sizing model with variable remanufacturing lot sizes has been shown to exhibit better performance than the benchmark model with fixed remanufacturing lot sizes. The new inventory lot-sizing model is anticipated to become a valuable decision-making tool in companies that are planning to adopt remanufacturing. The second decision-making tool was applied to address a production and inventory planning problem in a remanufacturing system considering different remanufacturing policies for a given remanufacturing strategy. For a remanufacture-to-stock system with two quality remanufacturables groups four alternative policies were examined, a policy which specifies simultaneous processing utilising dedicated resources was shown to be the best policy to achieve a shorter remanufacturing cycle time. For a remanufacture-to-order system with two quality remanufacturables groups, the three relevant policies of the four alternative policies were examined, a policy which specifies sequential processing and switching between various quality remanufacturables groups was shown to be the best policy to achieve a shorter remanufacturing cycle time. The production and inventory planning simulation models in a remanufacturing system are expected to become significant decision-making tools in remanufacturing operations.     

Dynamic performance of a hybrid inventory system with a Kanban policy in remanufacturing process

In this paper we study a hybrid system with both manufacturing and remanufacturing. The inventory control strategy we use in the manufacturing loop is an automatic pipeline, inventory and order based production control system (APIOBPCS). In the remanufacturing loop we employ a Kanban policy to represent a typical pull system. The methodology adopted uses control theory and simulation. The aim of the research is to analyse the dynamic (as distinct from the static) performance of the specified hybrid system. Dynamics have implications on total costs in terms of inventory holding, capacity utilisation and customer service failures. We analyse the parameter settings to find preferred “nominal”, “fast” and “slow” values in terms of system dynamics performance criteria such as rise time, settling time and overshoot. Based on these parameter settings, we investigate the robustness of the system to changes in return yield and the manufacturing/remanufacturing lead time. Our results clearly show that the system is robust with respect to the system dynamics performance and the remanufacturing process can help to improve system dynamics performance. Thus, the perceived benefits of remanufacturing of products, both environmentally and economically, as quoted in the literature are found not to be detrimental to system dynamics performance when a Kanban policy is used to control the remanufacturing process.     

废旧产品回收再制造计划模式研究述评

在分析再制造基本概念及流程的基础上,从废旧产品回收计划、回收产品拆卸计划、再制造生产计划等三个方面对国内外再制造计划模式的研究现状进行综述。指出目前研究中对再制造过程的不确定性特征认识不足、对产品回收后的状态不能有效预测、对不确定情形的产品拆卸计划研究较少、对于再制造生产计划与控制缺乏系统研究。针对上述不足,提出了进一步研究的方向。     

基于产品质量内生的制造/再制造最优生产决策

从制造商的视角出发,将产品质量水平作为内生变量,并考虑质量水平对返回废旧产品的降级率的影响,分别讨论单寡头、双寡头非合作以及双寡头合作市场中,制造商最优制造/再制造决策策略.根据需求市场对产品价格和质量水平的敏感性,进行经济性分析,权衡制造商的制造/再制造的收益、生产成本,优化产品质量水平,帮助企业决定合理的再制造比例.研究结果显示:随着降级率的增大,制造商会降低再制造比例;制造商设置的降级率在不同模式下对利润与价格的影响是有差异的.     

A COMPARISON OF PRODUCTION SCHEDULING POLICIES ON COSTS,SERVICE LEVEL,AND SCHEDULE CHANGES

We consider a single product, single level, stochastic master production scheduling (Mps ) model where decisions are made under rolling planning horizons. Outcomes of interest are cost, service level, and schedule stability. The subject of this research is the Mps control system: the method used in determining the amount of stock planned for production in each time period. Typically, Mps control systems utilize a single buffer stock. Here, two Mps dual-buffer stock systems are developed and tested by simulation. We extend the data envelopment analysis (dea ) methodology to aid in the evaluation of the simulation results, where Dea serves to increase the scope of the experimental design. Results indicate that the dual-buffer control systems outperform existing policies.     

考虑不同回收质量等级的再制造系统回收生产决策

废旧产品的回收再制造过程往往在回收质量、再制造成本、再制造产出率、再制造产品需求等方面存在不确定性因素,极大地增加了再制造生产管理决策的复杂性。本文在一个回收再制造系统中研究了存在多种回收质量等级时的两阶段回收—再制造联合优化决策问题,并扩展到需求与价格相关和再制造产出率随机两种情形。在最大化再制造商期望利润的决策目标下,基于每种回收质量等级的单位回收和再制造成本构造出再制造系统的有效生产前沿面,给出了不同决策情形下再制造商的最优回收数量、销售定价的解析解,并且分析了一些主要的参数对再制造商最优决策的影响。本文的研究结果表明：（1）含有多种回收质量等级的再制造系统中存在一个下凸的有效生产前沿面,不在该前沿面上的任何质量等级的回收产品都将不会被用于再制造;（2）在同等的政府补贴额度下,回收补贴方式对再制造商决策的影响程度大于再制造补贴方式;（3）当再制造品的市场需求与价格相关时,最优销售价格至少大于第一种被使用的回收质量等级的边际回收和再制造成本;（4）任意两种回收质量等级之间存在着替代或互补效应,由其成本差异决定,并且这种效应随着需求不确定性的增大而增大;（5）再制造产出率的不确定性和再制造品需求的不确定性之间存在"对冲"效应,这种效应随着再制造产出率不确定性的降低而减弱。本文的研究可为不确定性环境下再制造企业的回收、生产管理决策提供有益的管理启示。     

基于库存价值改变和随机需求的经济订货批量模型

大多数库存研究的重点都集中在各种复杂的限制条件和模型的变换上.没有考虑到库存本身可能发生贬值或增值的情况,而实际中库存本身常常会发生价值变化.针对以往库存模型中没有考虑库存价值变化的问题,提出了在需求为随机连续分布、库存价值发生变化情况下的单周期经济订货批量模型,给出了最优订货策略.模型中以先进先出为假设条件,基于报童模型的思想,以订货量为决策变量、期望收益为目标函数,结合随机需求的分布情况得到最优订货量和最大期望收益,并给出了相应的数学证明.通过算例对模型进行说明,并对影响最优订货批量和最大期望收益的各个参数进行敏感性分析.     

产品市场纵向差异的两阶段再制造供应链契约协调

针对常规产品与再制品销售市场的纵向差异和常规材料价格随机波动的情况,建立了"制造商-回收商"Stackelberg博弈模型,设计了考虑常规材料价格信息更新的两阶段回收费用共担再制造供应链契约协调机制,证明了两阶段可变契约的效益高于单阶段固定契约。算例分析表明两阶段可变契约的有效性:常规材料价格随机波动幅度越大,两阶段契约的改善程度越高;且协调机制能夠鼓励废旧产品的再制造,实现经济效益与社会效益的双赢。     

Design and implementation of a Drum-Buffer-Rope pull-system

Purpose: This paper investigates the selection, design and implementation of a Drum-Buffer-Rope (DBR) type of production pull-system in a panel fabrication plant characterised by extensive shared, batch resource resources within a low volume UK manufacturer of large vehicles. This was the second of a series of two related research projects conducted under the aegis of a Lean initiative at this case firm.

Design/methodology/approach: A purposively selected longitudinal case study conducted over 24?months and organised around a two phase research design. The initial body of evidence included a detailed map constructed by a project team of eight managers and accountants during a two day structured workshop; numerous unstructured interviews and observation of shop floor practices; document and archival analysis, and 140 photographs of the focal operation. Supplemented by extensive financial and operational data extracted from the firm’s accounting and MRP systems, including all data necessary to construct and implement bespoke capacity planning, work in progress (WIP) monitoring and simulation modelling tools. The case firm is anonymised.

Findings: The Lean manufacturing literature ignores the real-world issue of shared resources, and this gap is attributable to the concept of ‘rightsizing’ tools and equipment that is widely promoted within the Lean community. The case panel plant is characterised by extensive shared resources; many of which are also batch processes. The most appropriate pull-system method for this production environment is DBR. The detailed design of the DBR mechanism required a controlled transfer buffer of overhead conveyance capacity after the Drum because the extent of downstream process variability risked it being unable to offload panels, hence compromising throughput.

Research limitations/implications: The study is based upon a single case. This consequently has implications for the ability to generalise from the results.

Practical Implications: When the DBR pull-system design was implemented it reduced the number of panels in WIP by 60%. This equated to a 56% (18?days worth) reduction of manufacturing lead time and more than doubled the plant’s inventory turns (from 9.1 to 21.2). It also significantly improved delivery schedule adherence, with downstream jig stoppages in the Final Assembly falling from an average of six to less than one per week. The financial benefit was independently audited to equate to an annualised value of $850?K. Consequently, this project was awarded the first prize at its parent enterprise’s annual worldwide process improvement competition.

Originality/value: This paper details a novel technique that permits the routings of multiple value streams to be mapped and is useful for highlighting the identity and location of shared resources. It also contributes significantly to the literature that is available on the relationship between the Lean paradigm and the management of shared production resources, and adds to the literature on the detailed design and implementation of a DBR pull-system in a jobbing-type of environment.     

A shelf-space optimization model when demand is stochastic and space-elastic

The more customer demand is impulse-driven, the more it is space-dependent and the more it is subject to variation. We investigate the corresponding problem of retail shelf-space planning when demand is stochastic and sensitive to the number and position of facings. We develop a model to maximize a retailer׳s profit by selecting the number of facings and their shelf position under the assumption of limited space. The model is particularly applicable to promotional or temporary products.We develop the first optimization model and solution approach that takes stochastic demand into account, since the current literature applies deterministic models for shelf-space planning. By the means of an innovative modeling approach for the case with space- and positioning effects and the conversion of our problem into a mixed-integer problem, we obtain optimal results within very short run times for large-scale instances relevant in practice. Furthermore, we develop a solution approach to account for cross-space elasticity, and solve it using an own heuristic, which efficiently yields near-optimal results. We demonstrate that correctly considering space elasticity and demand variation is essential. The corresponding impacts on profits and solution structures become even more significant when space elasticity and stochastic demand interact, resulting in up to 5% higher profits and up to 80% differences in solution structures, if both effects are correctly accounted for. We develop an efficient modeling approach, compare the model results with approaches applied in practice and derive rules-of-thumb for planners.     

Multi-site aggregate production planning with multiple objectives: A goal programming approach

This paper addresses the problem of aggregate production planning (APP) for a multinational lingerie company in Hong Kong. The multi-site production planning problem considers the production loading plans among manufacturing factories subject to certain restrictions, such as production import/export quotas imposed by regulatory requirements of different nations, the use of manufacturing factories/locations with regard to customers' preferences, as well as production capacity, workforce level, storage space and resource conditions of the factories. In this paper, a multi-objective model is developed to solve the production planning problems, in which the profit is maximized but production penalties resulting from going over/under quotas and the change in workforce level are minimized. To enhance the practical implications of the proposed model, different managerial production loading plans are evaluated according to changes in future policy and situation. Numerical results demonstrate the robustness and effectiveness of the developed model.     

Remanufacturing of mobile phones—capacity, program and facility adaptation planning

Successful remanufacturing of mobile phones must meet the challenges of continuously falling prices for new phone models, short life cycles, disassembly of unfriendly designs and prohibiting transport, labor and machining costs in high-wage countries. A generic remanufacturing plan for mobile phones is developed. For the planning of remanufacturing capacities and production programs, a linear optimization model is introduced. To support the planner in the periodic adaptation of an existing remanufacturing facility under quickly changing product, process, and market constraints, discrete-event simulation is applied. Uncertainties regarding quantity and conditions of mobile phones, reliability of capacities, processing times, and demand are considered. The simulation model is generated by an algorithm using results from the linear optimization approach.     

基于投产点库存的随机综合生产计划模型研究

以企业基于投产点法的生产与库存控制策略为研究起点,分析了随机需求条件下生产系统服务水平与库存水平的数量关系,并将产品在计划期间的平均库存量引入综合生产计划模型。模型中计划期产量是与产品需求具有相同分布的随机变量,模型的优化目标是通过确定最佳的投产库存量和生产系统服务水平,求得相应的计划期产量区间。提出了模型的计算机辅助求解算法,并采用案例分析验证了模型的有效性。     

Education: MRP/GT: A FRAMEWORK FOR PRODUCTION PLANNING AND CONTROL OF CELLULAR MANUFACTURING

American industry typically uses material requirements planning (MRP) for manufacturing control. This paper presents production planning and control procedures based on group technology (GT), which is used in British manufacturing. A translation between these ideas and the American approach is made, and it is suggested that a combination of MRP and GT is viable. The problems that arise, especially in the areas of lot-sizing and sequencing/scheduling, and their possible solutions are discussed. Since increased adoption of GT is expected within the next decade, an intensified research effort is warranted in these and other areas so that existing MRP systems can be modified or extended to handle cellular manufacturing control problems. Subject Areas: Material Requirements Planning and Production/Operations Management.     

DIAGNOSING ORDER PLANNING PERFORMANCE AT A NAVY MAINTENANCE AND REPAIR ORGANIZATION,USING LOGISTIC REGRESSION

We present a tool to diagnose the behavior of planners in complex production processes and to establish improvement potential for the delivery performance by changing the planning behavior. Scientific literature on production control offers valuable knowledge, but the complexity of real‐life processes makes it impossible to directly apply this knowledge in real‐life. The presented tool identifies possible deficiencies in the current way of managing the business processes, by matching the scientific knowledge on order planning with data reflecting the real‐life processes via logistic regression. A case study at a maintenance organization illustrates the diagnosis tool.