Automated Disassembly of Electr(on)ic Equipment

Transcription

1 Automated Disassembly of Electr(on)ic Equipment R. Knoth, M. Brandstotter, B. Kopacek, and P. Kopacek Austrian Society for Systems Engineering and Automation, Brunhildengasse 1 N5, A Vienna, Austria, Tel.: , Fax: knoth@ihrt.tuwien.ac.at Abstract Almost all end-of life possibilities - upgrade, re-use, recycling of materials - require some form of disassembly. Despite the high standard of automation for the assembly of electric and electronic equipment, the standard of automation for disassembling is still vely low and therefor dismantling is often done manually. The approach to automate disassembling processes of electr(on)ic equipment with disassembly cells and the development of aflexible semi - automatic disassembly cell for printed circuit boards (PCB) will be described and discussed. INTRODUCTION Waste from electrical and electronic equipment (WEEE) is constantly growing and considered environmental relevant. This puts the electrical and electronic industry in the focus of environmental considerations, which resulted in a clear societal need for take-back and recycling of electronic products within Europe and has already become compulsory in some countries (Belgium, Netherlands,..). Other countries are close to implement such legislation in the near hture (Germany, Austria,..). The European Commission prepared a WEEE directive proposal which aims 0 to prevent, 0 increase re-use and recycling and to minimize the environmental relevance of WEEE. In addition collection targets and quotes for recovery (recycling and re-use) are defined, depending on the product family the recovery rates are in the range of 70 to 90%. If we consider the huge amounts of WEEE which will become available for recovery today and in the next years our state-of-the-art end-of-life capabilities are completely insufficient. Therefore we have to strengthen various end-of-life possibilities such as upgrade, re-use, recondition, remanufacture, resale or recycling of materials. Almost all of them require some form of disassembly. DISASSEM 6 LY State of the Art Especially for electric and electronic products, there are several end of life options existing, namely: ' 0 upgrade, 0 reuse, recondition, 0 re-manufacture, 0 resale, recycling of materials and disposal. Almost all of them require some form of disassembly. Especially the development of new products out of reused components has a high potential to reduce the environmental impact. But until now this is done very rarely because there are nearly no recycled components on the market. With an intelligent form of disassembly it will be possible and economically feasible to extract the re-usable components in a greater amount. Until now a very high standard in the field of automation and robotics have been reached, butfocused only on assembly. Few parts of electronic scrap are recycled after disassembling, however, the degree of automation is still very low - only some pilot or demonstration projects are realised mainly in research institutes. Disassembling, as the first and most important point in the recycling process, will be a part of the industry with a high rate of expansion. Currently disassembling for recycling, if it is done anyway, is mainly a manual process. But with the enormous increasing amount of products to be recycled and therefore also to be disassembled, such as computers, printers, telephones and other electronic devices and all sort of household-equipment, it is necessary to automate this aim to increase efficiency. High flexibility and low-cost of disassembly processes will be necessary. The automation potential will be one of the most important productivity factors for this new production process and becomes a new challenge for engineering. The two main goals are: Reduce the costs of disassembling for optimizing the recycling processes and to create a humane working environment in disassembly factories X/02/% IEEE 290

2 Due to the particular characteristic and requirements of disassembling tasks, disassembling needs structures and methods for a semi-automated disassembling with both, use of manual and automated (e.g. robotised) workplaces to meet the requirements of a new life cycle strategy. New Concepts in Disassembly Existing concepts are very inflexible and only developed for a special task or product.,,stiff automatized disassembly in single purpose cells - only for one product (e.g. one type of PC s) - cannot be economically feasible today. The number of devices or parts to be collected and concentrated on the place of the disassembly cell is usually to low for a two shift operation of the cell. For example in the case of computer-keyboards of a distinct type all keyboards from whole Europe per year could be disassembled in three month by one fully automatized cell. Therefore for efficient, semi-automated disassembly two new approaches will be presented [ 11: 1) A modular system for developing flexible disassembly cells 2) The concept of disassembly families Flexible Disassembly Cell Figure 1 shows the parts necessary for a modular, flexible disassembly cell. According to the figure the main modules of such a cell are[2]: Industrial robots or handling devices with special features like high accuracy, path- and force control (disassembly robot). Special gripping devices for a broad spectrum of parts with different geometric properties and dimensions. Disassembly tools especially developed for distinct tasks and robots. Feeding systems for the products to be disassembled. Transport systems - similar as for assembly cells. Fixture systems for parts with different geometric properties and dimensions. Manual disassembly stations. Intelligent control units able to process information from external sensors. Electronic component database including data of reusable and remanufacturable parts. (,,low cost ) vision systems for part recognition. Various sensors for force and moment limitations, position, distance, etc. Storage systems for tools and parts. (Intell.) cell cam Lht I wce I Figure 1. Modules of an intelligent flexible disassembly cell These modules can be chosen and combined according to the necessities of a cell for a distinct disassembly family as described below. The designing of such a cell can be divided in: + Analyzing: Which parts are the most suitable ones for recycling? + Determination of the operations for disassembly of the selected components. Decision: manually or automatically? + Selection of the tools starting with the,,easiest operations. Disassembly Families Establishing of relevant products or product groups in disassembly families is a key factor for the whole disassembly system [3]. Here the optimum for the characteristics of disassembly, design and recycling must be found. These so called,,disassembly families are groups of similar or different products which are requiring nearly the same disassembly operations - carried out with the same disassembly tools. SEMI-AUTOMATIC DISASSEMBLY OF PRINTED CIRCUIT BOARDS The process can be divided into several steps which are performed successively. At the beginning PCBs (printed circuit boards) are dismantled form collected Electrical and Electronic Equipment manually. In this stage the flexibility of manual operators is used which allows the disassembly of equipment from various sources. After this manual disassembling procedure the PCBs are fixed on frames and enter the disassembly cell (Figure 2 and 3). 29 1

3 R ob0 t S ystem - RobotContm&.r Figure 2. Components of the disassembly cell Figure 3. Disassembly Cell 292

4 Figure 4. Vision System A recognition system (Fig. 4) with image processing - Vision System - identifies re-usable parts and toxic components on the PCB. This is done by comparing the shape and labels of the parts with a database containing information from manufacturers and information from the re-use market. To acquire the data, required for a selective disassembly, a high quality image detecting system in necessary. To localize and identify the reusable components on the PCB the vision systems must be able to reach a position in accuracy of 0,l mm (coordinates, etc.) and recognize the characters on the part (OCR - Optical Character Recognition). Components which are recognised as valuable or potentially hazardous are desoldered by laser or removed using special robotic grippers in the next process step. The combination of a special laser desoldering technology and special robot grippers allows us to remove a wide variety of electronic components from the processed PCB. The application of a laser desoldering process has several advantages compared to conventional techniques (e.g. hot air): the temperature of the dissoldering process can be controlled effectively the laser is flexible in view of shape and position of the different components the necessary time for the dissoldering process is very short due to the direct heat ransfer the laser beam can be focussed on the pins without heating the body of the components Summarising the applied laser technique causes minimal thermal stress for the components, which results in an extended life-time for the re-use components. Finally the disassembly process results in PCBs which are less environmental relevant and electronic components suitable for reuse. CONCLUSIONS Disassembly automation especially for electr(on)ic devices is absolutely necessary world-wide in the nearest future because of the dramatically increasing amount of electr(on)ic scrap. Today only some pilot projects in form 293

5 of fully automated single purpose solutions - and only for one distinct type of one product - are realised. Main problem is the collection and transportation of a sufficient amount of these products to one place. In our approach we make use of,,disassembly families - these are products which are disassembled similar. The presented disassembly cell removes re-useable and hazardous components from various PCBs and results in PCBs which are less environmental relevant and electronic components suitable for re-use. Resulting from semi-automated disassembly, the system will improve the working conditions considerably. The quality of the whole recycling process will be enhanced and the skill of the workers can be used for more sophisticated jobs. When this system proves a success it can be built world-wide and thereby create new jobs. As a further consequence of the disassembling process we are obtaining valuable information about the disassembly of EEE and we can determine which practical problems occur frequently. This helps us to evaluate existing design criteria for disassembly [4] and to develop new guidelines for disassembling. Probably this will stimulate the industry to develop products which can be disassembled and re-qualified more easily. The improved quality of the sorted materials will have a direct feedback to reduce the volume of landfills and decrease the use of primary materials. Both effects have an incontestable influence on the improvement of environmental conditions. REFERENCES [I] a) Kopacek, B., Kopacek, P.: Semi-Automised Disassembly. In: Proceedings of the 10 International Workshop on Robotics in Alpe-Adria-Danube Region (RAAD Ol), Vienna, May 16-18, b) Kopacek, B. and P. Kopacek (1999). The role of semi-automatized disassembly in recycling, in Proceedings of the 14th IFAC World Congress, Vol. A, p.67-72, Beijing. c) Kopacek, B. and P. Kopacek (1999). Intelligent Disassembly of Electronic Equipment, in Annual Re-. views in Control, Vol. 23, p , Elsevier Science Ltd. [2] a) Knoth, R.; Hoffmann, M., Kopacek, B.; Kopacek, P.: Intelligent Disassembly of Electronic Equipment with a Flexible Semi-automatic Disassembly Cell. In: Proceedings of the Joint International Congress Electronics goes green 2000+, Berlin, Sept , b) B. Kopacek and P. Kopacek, Intelligent Disassembly of Electronic Equipment, in Proceedings of the I IFAC Workshop on,,intelligent Assembly and Disassembly - IAD 98, pp , Oxford, UK, c) B. Kopacek and P. Kopacek, Intelligent Disassembly of Electronic Products, in Proceedings of the 2nd Symposium,, Eco-Efficient Concepts for the Electronics Industry Towards Sustainability - CARE INNOVATION 98, pp , Vienna, Austria, [3] a) G. Gschwendtner, Ph.D. Thesis, Vienna University of Technology, 1999 b) W. Oppolzer, Diploma thesis, Vienna University of Technology, 1999 [4] Designing technical products for ease of recycling; fimdamentals and rules for design, VDI-Richtlinie 2243, VDI Handbuch Konstruktion, Verein Deutscher Ingenieure,