Search

This paper considers disassembly sequencing problems subjected to sequence dependent disassembly costs. In practice, the methods for dealing with such problems rely mainly on metaheuristic and heuristic methods, which intrinsically generate suboptimum solutions. Exact methods are NP-hard and therefore unsuitable to most of the practical problems. Nevertheless, it is useful to have exact methods available that can be applied in order to check, at least medium sized problems, to what extent the heuristically obtained solutions deviate from the optimum solution. The existing exact approaches, which are based on integer linear programming (ILP), become unmanageable, even for the cases of modest product complexity. To alleviate this problem to some extent, the iterative method that has been proposed by Lambert (2006) is applied here. This method is based on repeatedly solving a binary integer linear programming (BILP) problem instead of an ILP problem. The method appears to converge sufficiently quickly to be valuable for dealing with medium sized problems. We then use the iterative method for the validation of a new heuristic method that is also proposed in this paper. Finally, both the heuristic and the iterative BILP methods are implemented on a cellphone from practice consisting of 25 components that are represented, according to a set of precedence relationships, via a disassembly precedence graph. [ABSTRACT FROM AUTHOR]

This paper is a survey of the presently available literature on disassembly sequencing, including the papers that are closely related to this topic. Disassembly theory is applied to complex products such as mechanical, electromechanical and electronic appliances. It is required for end-of-life processing and for maintenance and repair. Apart from these applications, disassembly is studied for supporting the analysis of assembly processes. Disassembly sequencing involves the search for all possible disassembly sequences and the selection of the optimum solution out of these. In each application, a slightly different approach can be observed, including level of detail, degrees of freedom, and the role of uncertainty. Disassembly sequencing also plays a major role in the modern design process and is an invaluable tool in concurrent engineering. Its connection with the more detailed or component level and the less detailed level or process level including logistics, is highlighted. This presentation of the state of the art is intended as a stimulus for further research in this interesting field. [ABSTRACT FROM AUTHOR]

This paper presents a method for determining the optimum disassembly sequence for selective disassembly of discarded complex products. This methodology has been developed within the framework of the increasing need for formulation of a theory on selective disassembly and the various purposes of it. The objective of the optimization is maximizing the economic performance of the disassembly process within given technical and environmental constraints. It is demonstrated that the method, that is based on graphs, can be used to generate optimum sequences according to various objectives in a straightforward way. Also a ranking of the most favourable alternative sequence is possible. This is important to the inclusion of other criteria in the model and in adaptation of the disassembly system to fluctuating parameters like material yields and constraints. Contrary to earlier work on generation of disassembly sequences, in selective disassembly all possible incomplete disassembly sequences are included. This considerably increases the number of disassembly sequences to be studied with respect to the number of possible assembly sequences. According to the method described here, the number of viable sequences is determined in a straightforward way. On the basis of a specific example the general methodology is discussed. [ABSTRACT FROM AUTHOR]