Our research has focused on the development of mathematical programming tools to support infrastructure decision-making for reverse production systems. In this paper we present a robust framework for strategic decision-making in recycling systems when uncertainty greatly affects the outcomes of the decisions. Parametric uncertainty is described by ranges on costs, prices and volumes. The maximum regret is defined as the deviation of the profit of the chosen design from the optimal profit of the best design under a particular realization of the parameters. The robust metric used is to minimize the maximum regret. This problem structure extends our earlier work on robust reverse production system design where a finite set of scenarios was proposed to capture the uncertainty. We develop a solution methodology using an upper and lower-bounding scheme on the robust objective function. The application of the approach is illustrated using a case study from the electronics industry.
In recent years, there has been increased focus by regulators, manufacturers, and consumers on the issue of product end of life management for electronics. This paper presents an overview of a conceptual study designed to examine the costs and benefits of several different Product Take Back (PTB) scenarios for used electronics equipment. The study utilized a reverse logistics supply chain model to examine the effects of several different factors in PTB programs. The model was done using the IBM supply chain optimization tool known as WIT (Watson Implosion Technology). Using the WIT tool, we were able to determine a theoretical optimal cost scenario for PTB programs. The study was designed to assist IBM internally in determining theoretical optimal Product Take Back program models and determining potential incentives for increasing participation rates.
Environmentally conscious manufacturing is an important paradigm in today's engineering practice. Disassembly is a crucial factor in implementing this paradigm. Disassembly allows the reuse and recycling of parts and products that reach their death after their life cycle ends. There are many questions that must be answered before a disassembly decision can be reached. The most important question is economical. The cost of disassembly versus the cost of scrapping a product is always considered. This paper develops a computational tool that allows decision-makers to calculate the disassembly cost of a product. The tool makes it simple to perform 'what if' scenarios fairly quickly. The tool is Web based and has two main parts. The front-end part is a Web page and runs on the client side in a Web browser, while the back-end part is a disassembly engine (servlet) that has disassembly knowledge and costing algorithms and runs on the server side. The tool is based on the client/server model that is pervasively utilized throughout the World Wide Web. An example is used to demonstrate the implementation and capabilities of the tool.
The objective of this paper is to create a framework for sustainable product systems while considering the economic and environmental aspects of products. Specifically, this paper addresses the development of a Factor X model to study the diffusion of eco-innovation strategies. An adaptive agent based simulation model is presented to deduce the artifact system level design principles (behaviors) for sustainable product development.
This paper addresses the disassembly planning of heterogeneous batches of returned products. Disassembly is used to enhance the release of material fractions for recovery. The mass fractions of materials that are actually released during the recovery process are not known in advance and henceforth decisions concerning disassembly are to be made under uncertainty. The present paper provides a stochastic programming method to deal with uncertainty and to assess the value of information.
When a product reaches its end of life, there are several options available for processing it including reuse, remanufacturing, recycling, and disposing (the least desirable option). In almost all cases, a certain level of disassembly may be necessary. Thus, finding an optimal (or near optimal) disassembly sequence is crucial to increasing the efficiency of the process. Disassembly operations are labor intensive, can be costly, have unique characteristics and cannot be considered as reverse of assembly operations. Since the complexity of determining the best disassembly sequence increases with the increase in the number of parts of the product, it is extremely crucial that an efficient methodology for disassembly process planning be developed. In this paper, we present a genetic algorithm for disassembly process planning. A case example is considered to demonstrate the functionality of the algorithm.
Disassembly problem is a current issue for industrial companies. Governments of different countries promote research in this field. This paper presents the following points. First a brief state of the art in disassembly planning. Next it exposes a solution for the disassembly problem of industrial products. It uses a combination between direct and indirect graph representation for the product, all components that have physical entity are considered as vertices of the graph. Edges of the graph represent the relationships between vertices. There are three different types of edges. First corresponds with accessibility and fastener restrictions. Second corresponds with direct relations between components without fasteners. Last one corresponds with contact relationships, which represent an indifferent choice of the vertices. Based on that representation the paper exposed a method to find the best sequence to disassemble a component. Costs of disassembling each component and of changing tool between each pair of vertices and different sequences of the disassembly are taken into consideration. This method consists in a function minimization defined in the graph domain. In the last point of the paper this method is tested with a remote control disassembly. This method gives a solution to the problem, if several solutions, with the same cost, exist then it gives all of them, and any one of these disassemble sequences could be used to achieve to the target component.
This paper presents a non-destructive disassembly method. It tries to make up for limitations of other methods based on contact surfaces. It uses a contact surfaces graph and shows an algorithm to obtain the movement sequence needed for the disassembly of two objects, using a composition of transfer movement. It performs a second filter to obtain the exact disassembly direction from the group of directions obtained from the contact surfaces. The filter employs a mobile robotic heuristic to feedback the contact surface graph throughout the disassembly process. The heuristic generates an environment map to infer the region where the probability of collision with the other objects is lower. To achieve the disassembly the paper presents a method for modeling the elements implied in the disassembly process. This virtual model of the environment allows us to quickly process the elements and the simulation of the movements for disassembly. This model can be used to either schedule the disassembly process or to test, during the design stage, whether the products can be easily disassembled.
Closing the product and material cycles has emerged as a paradigm for industry in the 21st century. Disassembly plays a key role in a life cycle economy since it enables the recovery of resources. A partly automated disassembly system should adapt to a large variety of products and different degrees of devaluation. Also the amounts of products to be disassembled can vary strongly. To cope with these demands an approach to generate on-line disassembly control sequences will be presented. In order to react on these demands the technological feasibility is considered within a procedure for the generation of disassembly control sequences. Procedures are designed to find available and technologically feasible disassembly processes. The control system is formed by modularised and parameterised control units in the cell level within the entire control architecture. In the first development stage product and process analyses at the sample product washing machine were executed. Furthermore a generalized disassembly process was defined. Afterwards these processes were structured in primary and secondary functions. In the second stage the disassembly control at the technological level was investigated. Factors were the availability of the disassembly tools and the technological feasibility of the disassembly processes within the disassembly system. Technical alternative disassembly processes are determined as a result of availability of the tools and technological feasibility of processes. The fourth phase was the concept for the generation of the disassembly control sequences. The approach will be proved in a prototypical disassembly system.
Because of the emergent legislation (e.g. WEEE and EOLV), environmental standards (e.g. ISO 14000) and a shift in consumer opinion toward environmentally superior products, there is an increased need for CAD integrated Design for Environment tools to assist the designer in the development of environmentally superior products (ESP). Implementing Design for the Environment practices is an extremely effective strategy, as it is widely believed that 95% of development costs are determined at this stage. Many methodologies and tools have been developed to perform environmental analysis; however, many existing methodologies are inadequately integrated in the design process. This paper addresses these problems and presents a CAD integrated DFE tool that has been under development in the authors' institutes for the last number of years.
Various studies have identified alternatives for tin-lead solder. Characteristics such as availability, melting point, shear strength, and solderability have led to different alternatives being recommended for different applications. The most critical effect is in reflow soldering, where tin- lead solder has been heated to 220 degree(s)C, and the recommended temperature for the alternative alloys is 260 degree(s)C. A different degree of preparation for lead-free technologies exists when comparing board subassemblies with components. Board finishes with lead-free materials have been used for years with varying success. Palladium-based component finishes have also been available, but the greatest concern for components exists in plastic-encapsulated packages. Moisture sensitivity of packages that will be heated 40 degree(s)C above current processing levels presents the potential of delamination and cracks.
This paper examines a range of problems associated with justifying investments in Manufacturing Technology and Information Technology. The appraisal of high technology projects is rather complicated in that the true costs and benefits of such strategic investments are hard to capture with conventional methods of economic decision making. This paper reviews the financial criteria currently used in practice and pinpoints why these criteria might be misleading. It is demonstrated in the paper that qualitative factors very often are the most influential factors to be considered when attempting to justify alternative investments that are environmentally responsible.
Organizations realize that a strong supporting logistics or electronic logistics (e-logistics) function is important from both commercial and consumer perspectives. The implications of e-logistics models and practices cover the forward and reverse logistics functions of organizations. They also have direct and profound impact on the natural environment. This paper will focus on a discussion of forward and reverse e-logistics and their relationship to the natural environment. After discussion of the many pertinent issues in these areas, directions of practice and implications for study and research are then described.
The service industry and the manufacturing industry are interlinked in a supply chain situation. Part of the effectiveness of some manufacturing industry environmental performance based on remanufacturing and recycling is dependent on service industry decisions. In the information technology arena, personal computers (PCs) are the hard equipment of the service industry. The end-of-life decisions made by the service industry, and in this case the banking industry will have implications for the amount of systems within the waste or reverse logistics stream for manufacturers. Looking at some of the issues (and presenting a model for evaluation) related to decision making concerning end-of-life disposition for PCs is something this paper investigates. The analytical hierarchy process (AHP) is applied in this circumstance. The development of the model, its application, and results, provide the basis for much of the discussion in this paper.
Life cycle concepts do not only serve as basis in assisting product developers understand the dependencies between products and their life cycles, they also help in identifying potential opportunities for improvement in products. Common traditional concepts focus mainly on energy and material flow across life phases, necessitating the availability of metrics derived from a reference product. Knowledge of life cycle processes won from an existing product is directly reused in its redesign. Depending on sales volume nevertheless, the environmental impact before product optimization can be substantial. With modern information technologies today, computer-aided life cycle methodologies can be applied well before product use. On the basis of a virtual prototype, life cycle processes are analyzed and optimized, using simulation techniques. This preventive approach does not only help in minimizing (or even eliminating) environmental burdens caused by product, costs incurred due to changes in real product can also be avoided. The paper highlights the relationship between product and life cycle and presents a computer-based methodology for optimizing the product life cycle during design, as presented by SFB 392: Design for Environment - Methods and Tools at Technical University, Darmstadt.
Life Cycle assessment is becoming a successful methodology for improving products and processes design from the environmental viewpoint. However, important difficulties can be already found when applying the methodology in SMEs. In this paper, a software application for simplifying LCA in SMEs is proposed. The streamlining takes place in the assessment phase, where qualitative and quantitative inputs are introduced in a fuzzy inference system, for assessing the level of impacts provoked by evaluating a set of predefined fuzzy rules. These rules have been developed by a group of experts in Chemical Engineering.
Remanufacturing environments involve a higher degree of system complexity when compared to traditional manufacturing environments due to the variability associated with the routing, processing times and demand. Many of the consequences of this system complexity can be dealt with through operational-based approaches using specialized production planning and control techniques. However, it is also possible to improve overall system performance through the analysis of appropriate structural issues such as facility layout. This paper presents the results of a simulation-based analysis of four different layout alternatives: traditional job shop, cellular, fractal and holonic. An analysis of each layout alternative is conducted while varying product complexity, dispatching rules, number of workcenters, number of part types, shop load and demand variability with respect to flow time, WIP and machine utilization. The results of the analysis reveal under which conditions each layout alternative would be preferred to achieve the best overall system performance.
In this paper, we examine the tradeoffs between increasing the number of buffers and increasing the capacity at the remanufacturing stations under numerous circumstances on such performance measures as expected total cost, average WIP inventory, throughput and average processing (remanufacturing) time when the remanufacturing stations are operating in uncertain environments. We model the remanufacturing system using an open queueing network with finite buffers and unreliable servers. In order to analyze the queueing network, we use the decomposition principle and expansion methodology. Each server in the system is subject to breakdown and has a finite buffer capacity.
In this paper, we consider a hybrid manufacturing system with two discrete production lines. Here the output of either production line can satisfy the demand for the same type of product without any penalties. The interarrival times for demand occurrences and service completions are exponentially distributed i.i.d. variables. In order to control this type of manufacturing system we suggest a single stage pull type control mechanism with adaptive kanbans and state independent routing of the production information.