This paper describes a design strategy for mechanical systems called clumping and its effect on product value during the ownership and retirement phases of its life-cycle. A “clump” is a collection of components and/or subassemblies that share a physical relationship and some common characteristic based upon user intent. Clumping for product ownership values, i.e. reliability and serviceability, aims to increase component accessibility. Clumping for product retirement issues, i.e. reuse, recycling, and disposal, seeks to form aggregations of components for material compatibility, thus decreasing disassembly cost. This paper gives a detailed description of life-cycle ownership and retirement assessment methods and how they can be adapted into an existing computer-based design aid. A refrigerator in-door ice dispenser serves as an illustrative example.

A growing concern about the environment, and especially about waste and landfill, has spurred research into the design of more environmentally benign products. A dramatic reduction in environmental impact can be made by recycling. A critical issue in recycling is the separation of joints in the disassembly process. In product recycling (also referred to as reuse) non-destructive disassembly is desired, whereas in material recycling destructive disassembly is allowed (e.g., shredding). This has an impact on the selection of fasteners. In this paper, we provide an overview of the issues involved and specifically we evaluate the selection of fasteners in the context of product recycling, material recycling, and technical aspects as documented in the new German standard VDI 2243, “Designing Technical Products for Ease of Recycling – Fundamentals and Rules for Design”. The results of this evaluation provide insight in future areas of research and fastener selection models for life cycle design.

This paper describes a method for evaluating the compatibility of a product design with respect to end-of-life product retirement issues, particularly recyclability. Designers can affect the ease of recycling in two major areas: 1) ease of disassembly, and 2) material selection for compatibility with recycling methods. The proposed method, called “clumping,” involves specification of the level of disassembly and the compatibility analysis of each remaining clump with the design’s post-life intent; i.e., reuse, remanufacturing, recycling, or disposal. The method uses qualitative knowledge to assign a normalized measure of compatibility to each clump. An empirical cost function maps the measure to an estimated cost to reprocess the product. The method is an integral part of our life-cycle design computer tool that effectively guides engineers to an environmentally responsible product design. A refrigerator in-door ice dispenser serves as an illustrative example.

Design is the evolution of information. This evolution usually begins with an ill-defined need for a product and ends with exact specifications for production, use and retirement or recycling. A number of researchers have hypothesized that capture and reuse of this evolving information has potential for improving the design process and the reuse of design information. Published work has used the terms design history , design rationale , design intent and corporate memory to describe the systems that manage the capture, storage and query of the evolving information. The development of these systems depends on attention to 13 outstanding issues identified in this paper.

This paper follows up the suggestion made in an earlier note that the disposal of products at the end of their useful life, and of by-products of their use, should be considered at the time of product design. Practical suggestions are made on how to incorporate the disposal perspective in a concurrent engineering team. Doing this will reduce the life-cycle cost, and incidentally encourage an approach to design that promotes full recoverability of materials and a safe environment. Taken together these recommendations will be instrumental in avoiding the privation and scarcity that will surely result from neglecting the far downstream perspectives of product development. The ideal of 100% recoverability of materials is held out as possible, provided solar power becomes viable soon. In the final section an initial set of disposability guidelines for designers is presented. They deserve to be deepened. Efforts to standardize recycling processes are essential to reduce the enormous variety existing today.

In this paper, the development of an Activity-based Cost (ABC) model is presented for use in design for demanufacture under the presence of uncertainty. Demanufacture is defined as the process opposite to manufacturing involved in recycling materials and product components after a product has been taken back by a company. The crux in developing an ABC model is to identify the activities that will be present in the demanufacturing process of a product, and afterwards assign reliable cost drivers and associated consumption intensities to the activities. Uncertainty distributions are assigned to the numbers used in the calculations, representing the inherent uncertainty in the model. The effect of the uncertainty on the cost and model behavior are found by employing a numerical simulation technique — the Monte Carlo simulation technique. The additional use of disassembly action charts allows the influence of the uncertainty to be traced through the cost model to specific demanufacture process and product design parameters.

This study develops a method to capture the broadest customer preference in a product line while minimizing the life-cycle cost of providing variety. The paper begins with an overview of product variety and its importance in overhead costs: supply chain, equipment and tooling, service, and recycling. After defining the product structure graph as a representation of variety, the paper introduces an approximate measure for the customer importance and life-cycle cost of product variety The cost measure utilizes the concept of late point identification which urges standardization early in the manufacturing process and differentiation at the end of the process. The variety importance-cost map allows engineers to identify cost drivers in the design of the product or the manufacturing system and seek improvements. The refrigerator door example illustrates the concept. On-going work seeks to validate and enhance the method with several companies from different industries.

A growing concern about the environment, and especially about waste and landfill, has spurred research into the design of more environmentally benign products. A dramatic reduction in environmental impact can be made by product remanufacturing in which, in contrast to material recycling, the geometrical form of the product is retained and its associated economical and environmental value preserved. Our long term goal is to postulate and validate design metrics which effectively and efficiently measure the remanufacturability of given designs. The principal goal in this paper is to identify design characteristics which facilitate remanufacturing. This is accomplished by addressing the principal driving factors for remanufacturing, as well as identifying existing remanufacturing guidelines, philosophies, and practices. This information is leveraged and evaluated by investigating the remanufacturability of a product which is not currently remanufactured — an automobile door. From this, some illustrative design changes which increase the remanufacturability of the automobile door are proposed.

This paper describes a schematic representation of product retirement specification that aids in design for recycling and reuse. In the past decade, a graphical representation of the assembly process, called the assembly fishbone diagram , has effectively assisted engineers to conduct design for assembly (DFA) and process failure modes and effects analysis (FMEA). On the other hand, environmentally conscious manufacturing requires engineers to make advanced planning for product retirement. This study investigates the use of the reverse fishbone diagram to model the disassembly and reprocessing sequence of a product at the end of its useful life. An industry-provided student project guided us to an initial definition of the reverse fishbone diagram that effectively led the students to analyze the recyclability and make practical redesign suggestions. The diagram is continuously adding more rigorous definitions and promises to be a central tool for evaluation of recyclability in a simultaneous engineering setting.

Design for disassembly involves evaluating the ease/difficulty of disassembling a product composed of multiple components. Existing methods primarily address the problem of disassembly planning and do not quantify the ease or difficulty of disassembly. The current research work specifically addresses the development of a design for disassembly methodology based on the quantitative assessment (i.e. metrics) of the disassemblability of the product. The formulation of the metrics is based on the factors to be considered for disassembling a product. In particular we are considering the potential application of the methodology to robotic disassembly for recycling and maintenance. While designing a product it is necessary to determine the numerical value of the metric in order to arrive at an acceptable design. This facilitates the comparison of different design solutions. The methodology developed in this paper can serve as a basis for identifying the optimal design.

This paper extends from our previous results which suggest that fastening and joining methods preferred for assembly and scrap-material recycling do not necessarily facilitate remanufacture. We identify, through collaboration with three remanufacturing companies, primary factors that determine the life-cycle fastening and joining cost of products that are remanufactured. These factors, that also determine life-cycle joint reliability, are the fastening or joining method specified during design, the disassembly and reassembly method used during remanufacture, and the repair policy. A reliability model was applied to describe the failure characteristics of the joint so that part failure and replacement costs can be estimated over a specified length of product service. We then present an illustrative sample search space and the resulting life-cycle costs. A larger search space would require the use of optimization methods to minimize life-cycle costs. The fastening and joining plan, consisting of the above three factors, is represented for genetic algorithm optimization to be used on larger search spaces in the future.

Virtually all of the material in today’s automobiles can technically be recycled. The challenge facing engineers is making this recycling process economical, especially for materials in such components as seats and instrument panels. Recycling these components requires the different materials to be separated so that each can be recycled individually. This separation can be accomplished either manually , where workers disassembly and sort the vehicle components by hand, or mechanically , where the vehicle is shredded and the materials sorted by properties such as conductivity and density. In this paper, the usefulness of including likely separation techniques in DFR guidelines is discussed. Three vehicles were dismantled at the VRDC as part of an effort to establish a baseline of current vehicle recyclability. Concurrently, this allowed examination of the effectiveness of the early design for recycling (DFR) efforts. The applicability of common design guidelines to the two types of separation is discussed, and a simple method for determining the appropriate separation process in the early stages of design is presented.

Recent concern for the environment has caused growing attention to recycling, both using recycled materials to make products and recycling products after use. Although environmentalists may be eager to buy recycled/recyclable products, other consumers may not be so easily convinced. It may also be difficult to convince manufacturers that it is beneficial to develop green products. This paper supports a joint project between engineering and marketing disciplines to determine the cost and value of an environmentally designed product. Specifically, this paper evaluates the resources spent to manufacture a green videocassette in comparison with a standard videocassette by performing a resource analysis. This analysis estimates the cost, time and energy necessary to produce both videocassettes. This paper also compares the value of the videocassettes in terms of performance and physical attributes.

A method for evaluating the ease of disassembly of products is presented. Its primary use is in designing products for recycling and making environmentally-related decisions, but it is also relevant to servicing and maintenance. The evaluation procedure is centered around a spreadsheet-like chart and uses a catalog of task difficulty scores. The scores were derived from work-measurement analyses of standard disassembly tasks and provide a means of identifying weaknesses in the design and comparing alternatives quantitatively. The requirements and considerations in developing the design tool are examined in light of the general problem of manufacturability metrics. The limitations of the method and future extensions are discussed.

This paper presents the concept and implementation of the Green Browser , which enables designers and consumers to share environmental information. We propose the conceptual scheme of the Green Browser called green life cycle model . This model is intended to represent the product’s environmental impacts over the stages of raw materials, use, recycling, and disposal. The Green Browser has been implemented using WWW and MOO to be able to deal with the strategy model, which is the key element of the green life cycle model. A case study on building the strategy model of refrigerator is presented to illustrate the strategy model.

This paper proposes a design chart incorporating demanufacturing complexity metrics in robust design for recyclability. The proposed recyclability map relates sort complexity and material recovery efficiency for major subassemblies. The map helps designers to reduce product retirement costs and scrap through the appropriate selection of design modularity, material selection and disassembly strategy. Our method focuses on the dismantling process associated with multiple product families and generations and incorporates changes in recycling process technology capabilities. The recyclability map allows designers to understand the effects of uncertainties in product recycling and helps them to reach a strategy that is insensitive to these changes. The paper uses recycling of an inkjet printer as a validation example.

This paper surveys end-of-life strategies currently used in the electronics and appliances industries and identifies product characteristics to guide designers to specify appropriate strategies. The survey indicates that characteristics such as wear-out life, design cycle, technology cycle, functional complexity, number of materials, number of parts and others are important in determining the end-of-life strategy. Two characteristics, product life and technology cycle, serve to demonstrate a possible categorization of products’ end-of-life path. The categorization leads to developing a methodology that guides product developers. By expanding the methodology to include all characteristics, designers will be able to specify end-of-life strategies, to seek environmentally friendly designs, and to develop new recycling technologies. This paper concludes with a proposed web-based application for identifying suitable product end-of-life strategies early in the design cycle of a broad range of products based on key product characteristics.

Increasingly, designers are asked to consider additional types of requirements, including the environmental impact of their designs during the product’s lifetime and after its useful life. Two of these types of requirements are investigated in this paper. Demanufacturing is the process of dismantling a product and preparing for the disposal or recycling of components, modules, or materials. Product reuse retains a greater portion its value and often requires remanufacturing , the refurbishment of a product or product modules. Assessments of a product’s ease of de- and remanufacture are often desirable at various stages during the design process. In this paper, requirements for CAD representations to support de- and remanufacture assessments are identified. Information requirements are classified into categories according to the difficulty in extracting the information from assembly-based CAD representations. Information not obtainable from CAD representations is noted. Methods for querying CAD systems to extract significant amounts of this information are presented. These methods have been incorporated into the prototypical CAD system CODA. This work is applied to the design for de- and remanufacture of an automotive instrument cluster. It is shown that feasible disassembly sequences can be generated, ideal parts can be recognized, disassembly times can be reliably estimated, and input can be generated for spreadsheet-based assessment tools.

In previous work, the idea of designing for the life cycle (DFLC) was investigated through the improvement of product architectures with an emphasis on increasing modularity. In this paper, that work is extended by developing a method for suggesting changes to the product to improve the correspondence between modules from different life-cycle viewpoints. Based on an analogy to the determination of critical paths in network analysis, the identification of limiting factors in a candidate design is intended to assist the designer in recognizing design changes that have the greatest impact on improving recyclability. The purpose of this paper is to illustrate how the identification of limiting factors can be used to improve product recyclability during configuration design. A general method for identifying and prioritizing the limiting factors is presented and applied in the context of improving recyclability. This method is shown to be capable of efficiently determining effective design changes to improve product modularity and recyclability. It is argued that the concept of limiting factors and the developed method are applicable to many different configuration design issues and not limited to recycling or even other DFLC issues. A validation of the limiting factor identification method is presented using a Genetic Algorithm and an exhaustive search.

Today’s increasing demands placed on vehicles in terms of increased power, reduced emissions, maintenance and energy consumption, and end of life cycle issues related to recycling and disposal have made vehicle life cycle design a very important issue. However, life cycle issues are typically not concurrently addressed during the development stages. In this paper, our interest is in determining vehicle frame design specifications that include technical as well as environmental life cycle considerations. The design of an electric vehicle space frame is used for our study. Technical performance and environmental life cycle considerations are taken into account, represented by the travel distance between charges and an environmental life cycle assessment, respectively. These considerations are mapped into structural and safety issues, which represent the critical vehicle frame design constraints. In order to rapidly explore the design space and perform trade-off studies, response surface models are constructed and used to characterize the physical behavior of the space frame. The purpose of our research is to provide designers with a decision support tool that will enable them to efficiently and effectively include and investigate life cycle considerations early in the design process. This is our primary emphasis in this paper, not so on the results of our example problem, per se.