Optimal Disassembly Sequence Research Articles

Determining optimum disassembly sequences in electronic equipment

This paper presents a study on disassembly sequence generation for electronic equipment. This is particularly useful because adequate end-of-life disassembly becomes crucial as take-back obligations are imposed for environmental reasons. Besides this, the hierarchical structure, typical to electronic products, makes product remanufacturing to an important topic. Methods from disassembly of mechanical assemblies are successfully adapted to these specific challenges. First, a modeling method for assemblies is described, which is aimed at automatically determining the optimum disassembly sequence. It is argued that the information, which is condensed in the connection diagram and the set of precedence relations, is sufficient for the automatic generation of such a sequence. Appropriate use of the precedence relations reduces the size of the model, that can be represented as an AND/OR graph with a restricted number of subassemblies and actions. With disassembly costs and revenues included, the optimum disassembly sequence can be found with standard linear programming software, thus without the need of visiting the complete search space. As a matter of fact, the size of the problem is strongly reduced, as it increases only linear with the number of parts in the assembly. It has been demonstrated that the model nearly instantaneously generates the optimum disassembly sequence. Besides this, the model can generate near optimum sequences as well, which is beneficial if multiple criteria are considered.

A Hybrid Disassembly Sequence Planning Approach for Maintenance

This paper describes a hybrid approach to handle disassembly sequence planning for maintenance. The product under maintenance is first modeled using a novel hybrid graph known as Disassembly Constraint Graph (DCG) which embodies complete disassembly information and can be used to prune the search space of disassembly sequences. Subsequently, a novel Tabu-enhanced GA engine is invoked to generate the near optimal disassembly sequences. A case study was used to illustrate the effectiveness of the proposed approach. The details of the DCG, the TS-enhanced GA engine and the fitness function used are presented in this paper.

Disassembly sequence generation: A Petri net based heuristic approach

The generation of a set of optimal or near-optimal disassembly sequences is an important task associated with the study of disassembly planning. This task encapsulates actions at the required disassembly depth to reach maximum net revenue while satisfying economic constraints. The Petri net modelling, combined with heuristic search procedures developed in this study, offers an efficient procedure for disassembly sequence generation. The heuristic generates and searches a partial reachability graph to arrive at an optimal or near-optimal disassembly sequence based on the firing sequence of transitions of the Petri net model. The proposed methodology reduces the search space in two areas: (1) pruning the disassembly tree (DT) and, (2) selective tracking of the reachability graph. The efficacy of the proposed methodology is demonstrated by using two examples from the literature.

Optimal Disassembly Sequence Using Genetic Algorithms Considering Economic and Environmental Aspects

In this paper, a genetic algorithm (GA)-based approach for an optimal disassembly sequence considering economic and environmental aspects is presented. All feasible disassembly sequences are generated by a disassembly tree or an AND/OR graph. Using the disassembly precedence and the disassembly value matrix, a disassembly sequence is optimised. The precedence of disassembly is determined through a disassembly tree or an AND/OR graph and the value of disassembly is induced by considering both economic and environmental aspects in the disassembly, recycling, and disposal phases. Economic and environmental factors can be compared by the same measure through converting environmental factors into economic cost. To solve the disassembly sequence problem, a heuristic algorithm based on GAs is developed. The proposed GA can search for and dynamically explore the disassembly node through the highest disassembly value, keeping their precedence in order to identify an optimal disassembly sequence. It can also help to explore the search space, and an optimal solution can be obtained by applying the optimisation criteria. A refrigerator is used as an example to illustrate the procedure.

An algorithm for optimising the servicing of products with constrained, multiple defects

The twin pillars of sustainable development are the conservation of natural resources and the management of waste. Waste is generated whenever a product is serviced or repaired, or when it is ultimately discarded at the end of its useful life. In order to manage such waste, the servicing options and costs must first be ascertained. This paper presents an algorithm for the generation of optimal disassembly and re-assembly sequences for the servicing of products with multiple defects, subject to constraints such as inaccessible components. The multiple service action (MSA) algorithm determines the minimum total servicing cost for a product network based on Floyd's Algorithm, a shortest path algorithm. Well-established shortest path algorithms, which compute the shortest route between any pair of nodes in a network, are unable to handle multiple defects. The product network is first constructed, depicting the components and subassemblies as nodes, and embodying in directed arcs, the labour, materials and tooling costs associated with disassembly and re-assembly, as well as the cost to repair, reuse, recycle or dispose the defective components. The MSA algorithm was tested on seven different product networks representing multiple defective components that can be serviced by different feasible routes. For each feasible service route, associated costs were computed. It was established that the algorithm was able to generate optimum disassembly and re-assembly routes for the servicing of products with multiple defects subject to constraints.

A Method for Sequencing the Disassembly of Products

In this paper a method for the creation of optimum disassembly sequences is described. The method takes a graphical representation of the product's structure and maps component disassembly cost and recovery value, along with disassembly equipment requirements to the components within the product. From this data the product is broken down into sub-units of sequentially disassemblable component cells. All possible parallel disassembly options are then displayed and the disassembly sequence is optimised against the equipment available for the disassembly process.

Linear programming in disassembly/clustering sequence generation

Based on earlier research on optimal disassembly sequence generation, notably graphically supported search methods, a method for solving general optimal disassembly sequence generation problems by linear programming has been developed and described. This method puts no serious restriction to the size of the model. It is adaptable to changes in model structures and constraints, and it is even not restricted to divergent operations, such as disassembly. This is demonstrated by solving the combined disassembly/clustering problem. Clustering is the combination of different disassembly products to categories that can be considered — and sold — as a single product, e.g. steel parts. The theoretical model is validated and clarified by its application to some standard problems from literature.

Selective disassembly for virtual prototyping as applied to de-manufacturing

Selective disassembly involves separating a selected set of components from an assembly. Applications for selective disassembly include de-manufacturing (maintenance and recycling), and assembling. This paper presents a new methodology for performing design for selective disassembly analysis on the CAD model of an assembly. The methodology involves the following three steps: (i) identifying the components to be selectively disassembled for de-manufacturing by a software program or designer, (ii) determining an optimal (e.g. minimal cost) disassembly sequence for the selected components that involves a computationally efficient two-level reduction procedure: (a) the determination of a set of sequences with an objective of minimal component removals via a wave propagation approach that topologically order components in an assembly for selective disassembly, and (b) the evaluation of resulting sequences based on an objective function (e.g. minimal cost) to identify an optimal sequence, and (iii) Performing disassembly design decisions based on the evaluated optimal sequence. Preliminary implementation results of the selective disassembly methodology in sequencing and disassembly cost evaluation, and application of the selective disassembly technique for de-manufacturing assessment are presented.

Economical evaluation of disassembly operations for recycling, remanufacturing and reuse

This paper introduced a procedure which integrates economical factors into the scheduling of disassembly operations for Material Recovery Opportunities (MRO). MRO are defined as opportunities to reclaim post-consumer products for recycling, remanufacturing and reuse. Traditionally, recyclers have resorted to using heuristics for analysing the breakdown of products and the associated costs. In this paper, a quantitative method of disassembly analysis is developed. Its aim is to improve the efficiency of the disassembly planning process and to generate an optimal disassembly sequence which maximizes profit. Three economic indices are used to evaluate the trade-off between reclamation and disposal of individual components. A systematic procedure of generating an optimal disassembly sequence based on maximizing the profits of material recovery is presented. Three criteria are established to reduce the search space and facilitate recovery opportunities: (1) material compatibility, (2) clustering for disposal, and (3) concurrent disassembly operations. An example is provided on a product being disassembled for recycling at a local recycling plant in Canada.

A geometric algorithm for single selective disassembly using the wave propagation abstraction

Disassembling a selected component from an assembly, defined as selective disassembly, is important for applications such as maintenance, recycling and reuse. This paper presents a geometric algorithm to solve the following selective disassembly problem: given an assembly and a selected component to be disassembled, determine the disassembly sequence with minimum component removals (motions), defined as an optimum sequence. We propose an abstraction “ wave propagation” that analyzes the assembly from the selected component outwards, and orders the components for selective disassembly. The main contributions of this research are: (1) determining an optimal disassembly sequence; (2) reducing the search space by analyzing a subset of components in the assembly; and (3) providing a polynomial average complexity algorithm. The proposed selective disassembly approach applies to both two dimensional and three-dimensional assemblies.

An evaluation methodology for disassembly processes

Disassembly is a systematic process that allows reusable, non-recyclable, and hazardous subassemblies to be selectively separated from recyclable ones. In this paper, we present a methodology to evaluate different disassembly strategies so that the best one could be chosen. Since the identification of all possible disassembly sequences of complex products is not an easy task, we also propose a disassembly sequence generation heuristic which gives a near optimum disassembly sequence for a product. The application of the methodology is illustrated by considering an IBM PS/2 Model 30 computer base.

Optimal disassembly of complex products

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.

Machine Assembly/Disassembly Planning by Cooperative Agents.

A machine assembly/disassembly planning system based on agent cooperation has been developed. It can create an optimal assembly and/or disassembly sequence for any goal, such as the disassembly/assembly of all parts or the replacement of a broken part. The planning system is reactive, i.e.. it can cope with unpredictable incidents, such as modification of the goals while the system is operating. We define twenty six class agents for machine assembly/disassembly planning tasks and use an improved algorithm the original of which was proposed by P. Maes. The framework of the proposed planning system and detailed difinition of the planning algorithm are introduced and the results of experiments are discussed.

Planning product disassembly for material recovery opportunities

SUMMARY This paper addresses an increasingly important aspect of product design and its relationship to life-cycle costing: disassembly for material recovery opportunities (MRO). MRO is defined as an opportunity to reclaim post-consumer products for recycling, remanufacturing and re-use. The authors have developed a methodology which can be used to identify and assess cost-effective characteristics of disassembly for the recovery of products. The central focus of this paper is aimed at improving the efficiency of the disassembly planning process and generating an optimal disassembly sequence. Four criteria are established to optimize the generation of the disassembly sequence: (1) material compatibility, (2) clustering for disposal, (3) concurrent disassembly operations, and (4( maximizing yield. In this paper we define the ‘disassemblability’ of a product as the ability to optimize the design and disassembly process for removal of specific pans or materials in a manner which will minimize costs. Steps ha...

回転機能部品の部品展開手法に関する研究(第2報)

This study deals with the automatic determination of part specifications from assembly drawings, such as the assembly sequence and the distribution of tolerances. This paper describes a new algorithm for generating assembly/disassembly sequence of functional machine unit. The algorithm is based on a data model of assembly structure described by connective relations among parts. The algorithm for generating disassembly sequence can be divided into three stages. In the first stage, a set of parts are listed as candidates to be disassembled. In the second stage, one part is selected from the set according to the rules arranged in the order of the ease of disassembly. In the third stage, the selected part is actually disassembled using an appropriate procedure. These three stages are executed recursively until all parts are disassembled. This paper also discusses an optimal disassembly sequence to minimize the number of the changes of direction in disassembly and the number of tools changes. This algorithm is implemented as a rule based system in Prolog. Through the experiments on the machine units, including a headstock of eighty parts. The solutions are the same to those determined manually by skilled engineers.