Askiner Gungor

Issues in environmentally conscious manufacturing and product recovery: a survey

Environmentally Conscious Manufacturing and Product Recovery (ECMPRO) has become an obligation to the environment and to the society itself, enforced primarily by governmental regulations and customer perspective on environmental issues. This is mainly driven by the escalating deterioration of the environment, e.g. diminishing raw material resources, overflowing waste sites and increasing levels of pollution. ECMPRO involves integrating environmental thinking into new product development including design, material selection, manufacturing processes and delivery of the product to the consumers, plus the end-of-life management of the product after its useful life. ECMPRO related issues have found a large following in industry and academia who aim to find solutions to the problems that arise in this newly emerged research area. Problems are widespread including the ones related to life cycle of products, disassembly, material recovery, remanufacturing and pollution prevention. In this paper, we present the development of research in ECMPRO and provide a state-of-the-art survey of published work.

Disassembly line in product recovery

There are several situations in a product recovery environment where products may be disassembled for economical and regulatory reasons. The disassembly line is perhaps the most suitable setting for disassembly of large products (consisting of numerous components) as well as small products received in large quantities. This paper discusses the importance of a disassembly line in product recovery. The objective of the disassembly line is to utilize the available resources as efficiently as possible while meeting the demand for recovered parts. However, there are many complicating matters that need to be considered to create an efficient disassembly line. Our primary goal is to discuss these issues and provide a better understanding of the complications and their effects on the disassembly line. We also demonstrate how some important factors in disassembly can be accommodated to balance a paced disassembly line by modifying the existing concept of assembly line balancing. An example is presented to illustrate the approach.

Petri net approach to disassembly process planning for products with complex AND/OR precedence relationships

Abstract We present a Petri net (PN)-based approach to automatically generate disassembly process plans (DPPs) for product recycling or remanufacturing. We define an algorithm to generate a geometrically-based disassembly precedence matrix (DPM) from a CAD drawing of the product. We then define an algorithm to automatically generate a disassembly Petri net (DPN) from the DPM; the DPN is live, bounded, and reversible. The resulting DPN can be analyzed using the reachability tree method to generate feasible DPPs, and cost functions can be used to determine the optimal DPP. Since reachability tree generation is NP-complete, we develop a heuristic to dynamically explore the v likeliest lowest cost branches of the tree, to identify optimal or near-optimal DPPs. The cost function incorporates tool changes, changes in direction of movement, and individual part characteristics (e.g., hazardous). An example is used to illustrate the procedure. This approach can be used for products containing AND, OR, and complex AND/OR disassembly precedence relationships.

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.

Disassembly sequence planning for products with defective parts in product recovery

Recycling and remanufacturing are important forms of product/material recovery which involve product disassembly to retrieve the desired parts and/or subassemblies. Disassembly is a systematic method for separating a product into its constituent parts, components or other groupings. Efficient disassembly requires development of disassembly sequence plans (DSPs). Generating DSPs describing the sequence of parts during disassembly is not a trivial problem since DSP generation is described to be NP-complete. Further complicating matters is the presence of a high degree of uncertainty due to upgrading/downgrading of the product during its use by the customers and defects occurring either when in use or during disassembly. In this paper, we address the uncertainty related difficulties in disassembly sequence planning. To this end, we present a methodology to develop a framework for dealing with uncertainty in DSP implementation and demonstrate it using a simple example.

A solution approach to the disassembly line balancing problem in the presence of task failures

In this paper, we discuss the disassembly line balancing problem in the presence of task failures (DLBP-F). There are precedence relationships among disassembly tasks and the tasks must be completed within a given time, determined by the demand in a given period. However, if a task (or more than one task) cannot be performed because of some defect, some or all of the remaining tasks may be disabled due to the precedence relationships among tasks. This may result in various complications in the flow of workpieces on the disassembly line, e.g. early-leaving, self-skipping, skipping, disappearing and revisiting workpieces. We discuss these complications and highlight their effects on the disassembly line. The problem is to assign tasks to workstations such that the effect of the defective parts on the disassembly line is minimized. This paper presents a solution procedure to the DLBP-F. An example is provided to illustrate the approach.

Disassembly sequence plan generation using a branch-and-bound algorithm

This paper presents an approach to generate disassembly sequence plans (DSP) automatically for product recycling and remanufacturing. An algorithm is defined first that generates a geometrically based disassembly precedence matrix (DPM) from a CAD drawing of the product. The DPM is then used to generate a hierarchical disassembly tree (HDT) that represents the feasible DSP. Generation of the HDT, i.e. generation of all feasible DSP, is NP-complete. Thus, to keep the size of the HDT manageable, the branching and bounding processes are controlled using two user-defined variables. The first, w , controls the enumeration of the HDT, while the second, v, controls the bounding procedure in the HDT along with an evaluation function. The evaluation function incorporates tool changes, changes in direction of movement during disassembly along with individual part characteristics (e.g. high-valued parts, parts with hazardous content, etc.). The resulting HDT is called the reduced HDT (RHDT) since it only represents as many (near-) optimum DSP as the size of v. Experimental results demonstrate the applicability and effectiveness of the methodology.

A petri net approach to disassembly process planning

Recycling and remanufacturing involve product disassembly to retrieve the desired parts and/or subassemblies. Disassembly is a systematic method for separating a product into its constituent parts, components, or other groupings. Disassembly process planning is critical in minimizing the amount of resources (e.g., time and money) invested in disassembly and maximizing the level of automation of the disassembly process and the quality of the parts (or materials) recovered. We propose an algorithm which automatically generates a disassembly Petri net (DPN) from a geometrically-based precedence matrix. The resulting DPN can be analyzed to generate all feasible disassembly process plans (DPPs), and cost functions can be used to determine the optimal DPP; alternatively, heuristic methods may be used to generate near-optimal DPPs.

Evaluation of connection types in design for disassembly (DFD) using analytic network process

Design for disassembly (DFD) is an important design concept to make products more friendly for maintenance and remanufacturing practices. One of the important issues in DFD guidelines is related with the selection of the connectors used in the product. This paper evaluates the alternative connection types using the powerful analytic network process (ANP). The paper generates a complete ANP model, which includes all important aspects of connector selection. The model presented evaluates alternative connectors by including the three main concerns: (1) making product disassembly friendly; (2) making product assembly efficient; and (3) increasing the product performance when it is in-use. The results obtained from the model can benefit designers in making better decisions on selecting connectors to be used in the product. Benefits of the approach is detailed through illustrative example. q 2006 Elsevier Ltd. All rights reserved.

Disassembly process planning using Petri nets

We generate a disassembly PN (DPN) from a disassembly precedence matrix. The resulting DPN can be analyzed using the reachability tree method to generate all feasible disassembly process plans (DPPs), and cost functions can be used to determine the optimal DPP. Since generating the reachability tree is NP-complete, we develop a heuristic algorithm to limit the size of the reachability tree. The algorithm employs multi-hypothesis search to dynamically explore the /spl nu/ likeliest lowest cost branches of the tree, in order to identify near-optimal DPPs. The cost function incorporates tool changes, changes in direction movement, and individual part characteristics (e.g., hazardous). An example is used to illustrate the procedure.