Finding an efficient way for determining a near-optimum disassembly sequence for complex products is becoming an important challenge for many industries, given the increasing environmental awareness of both governments and society. As a first approach, mathematically exact methods can be used to deal with this problem. But when disassembly
costs that are dependent on the sequence and the number of components inside the product structure are prohibitive, heuristics or artificial intelligence-based methods are normally much more suitable to fulfill industry requirements. Nevertheless, when the size of the instance is very large, sequential algorithms are too slow. In this paper, a multi-start, greedy heuristic is defined and tested on a sample of products previously developed to measure the performance of a Scatter Search metaheuristic dealing with the same problem. The performance of the new algorithm was demonstrated to be competitive when compared with the one done under Scatter Search. It is also notably faster especially as the number of components inside the product structure increases.
In recent decades, regulations and markets have been exerting pressure on designers and manufacturers to take more responsibility for the environmental impacts of their products throughout their life cycles. The problem of finding the disassembly sequence represents one of the major challenges when attempting to close product life cycles by carrying out reuse, recycling and remanufacturing practices. Many different techniques have been used to deal with this problem, varying from exact to heuristic solutions. So far, however, not much effort has gone into measuring and comparing the efficiency of this wide set of techniques. This is partly due to the difficulties of getting a wide population of real products, belonging to different industries and with different degree of complexity that might constitute a representative population for carrying out this kind of task. In this paper, a generator of complex products is presented that is able to build up products with hundreds of components joined by different kinds of joints in such a way that a theoretical “good” disassembly sequence is always known. The efficiency of different methods for general products can thus be easily compared. The performance of a Scatter Search algorithm is tested as an example of its application in this case.
KEYWORDS: Computer aided design, Manufacturing, Solid modeling, CAD systems, Robotics, Chemical elements, Systems modeling, 3D modeling, Prototyping, Process modeling
European environmental legislation has significantly evolved over the last few years, forcing manufacturers to be more environmentally aware and to introduce ecological criteria in their traditional practices. One of the most important goals of this set of regulations is to reduce the amount of solid waste generated per unit of time by promoting recycling, repair, reuse and other recovery strategies at the product end of life (EOL). However, one of the most difficult steps for manufacturers is that of deciding which of these options or which combination of them should be implemented to get the maximum recovery value taking into account the specific characteristics of each product. In this paper, a recurrent algorithm is proposed to determine the optimal end-of-life strategy. On the basis of the product bill of materials and its graphical CAD/CAM representation, the model will determine to what extent the product should be disassembled and what the final end of each disassembled part should be (reuse, recycling or disposal). The paper starts by presenting an
overview of the model, to then focus on the CAD-integrated algorithm for determining the optimum disassembly sequence, a necessary step in EOL decision-making.
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.
The selection of the optimal disassembly plan is a key problem in the design of many industrial processes, given its influence in the final cost of products. Design for disassembling is of increasing importance mainly due to environmental management and maintenance accessibility concerns. In this paper we study the selection of a good disassembly plan, based on the knowledge of initial separation costs for any couple of components. We have developed a rational way of evaluating the separation cost for any number of different components, based on the given binary costs. As recursive exploration of the solution tree is not a practical procedure for real problems, a heuristic approach was developed. This procedure was used to solve a real problem: the most convenient way of decomposing animal blood in slaughterhouses -a serious environmental concern- from an economic point of view, finally obtaining eatable proteins. This is converted into a disassembly problem, simply by considering blood proteins as the components of an assembly that must be separated into parts.
Conference Committee Involvement (4)
Environmentally Conscious Manufacturing VI
1 October 2006 | Boston, Massachusetts, United States
Environmentally Conscious Manufacturing V
23 October 2005 | Boston, MA, United States
Environmentally Conscious Manufacturing IV
26 October 2004 | Philadelphia, Pennsylvania, United States
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