Active Disassembly
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Active Disassembly (AD) is a developing technology which is associated with the term Active Disassembly using Smart Materials (ADSM)
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[edit] Outline
Smart materials such as shape memory alloys are now offering the possibility of allowing complex items to be disassembled easily and in a cost-effective manner. The development of this technology could make recycling of consumer products more common and thus serve to be environmentally friendly.[1]
[edit] Eco-design and legislative background
Companies designing and manufacturing a range of consumer goods are becoming increasingly subject to legislative and other pressures requiring them to consider the "End of Life" (EoL) implications of their products. The ELV (End of Life Vehicle) Directive in Europe, for example, states that the current reuse and recycling level of 75% (by weight) has to be raised to 85% by 2015[2]. The WEEE (Waste Electrical and Electronic Equipment) Directive is aimed at the eradication of landfill as a means of disposing of hazardous materials such as arsenic in LEDs. Manufacturers are also required to build strategies for disassembly into the design of their products. In the past designing products such as cars rarely involved consideration of what would happen when they were scrapped, although some companies, such as BMW have been pro-active in this respect.[3]
[edit] Research
Dr. Joseph Chiodo is the inventor of AD and ADSM technology. He focussed his research on thermally triggered disassembly using shape memory materials. He set up a company called "Active Disassembly Research" (ADR) which carries out its own research as well as working on behalf of other companies to develop and patent methods that can be used.
Since the 1980s this field gained an increased popularity by industry which lead to more extensive research. Dr. Neubert explored the field of active disassembly further by looking at other trigger methods to initiate disassembly. His conceptual ideas to use the volume increase of frozen water to disconnect certain parts of a product or to use soluble fasteners, are described in his dissertation published in 2000.
Dr. Barbara Willems elaborated on this research by focusing on the "pressure cells" described by Neubert. She developed a mathematical model to determine the optimal shape and dimensions of a pressure-activated fastener. Implemented in a product, these snap-fit-like fasteners enable dismantling through variations in ambient pressure. Since pressure variations are very unlikely to occur during the normal life-time of an electrical product, this trigger mechanism offers a more secure way of disassembly compared to temperature based triggering.
[edit] Advantages of AD
Most consumer products consist of a large number of parts and a wide range of materials. Disassembly at the end of a product's useful life is an inevitably complex and time consuming operation to ensure effective separation of all component parts for subsequent re-use or recycling. AD techniques permit the automation or semi-automation of this process and thus make it more viable. The incorporation of AD and the implications of companies taking responsibility for the end of life recycling of their products will have long term cost implications for the consumer.
[edit] The use of smart materials
A wide range of methods are being developed for use in AD. These methods generally require the use of smart materials which respond to a stimulus in order to change shape or size and thus facilitate the release of parts. The materials involved include Shape Memory Polymers (SMP) and Shape Memory Alloys (SMA). These materials offer significant shape changes at a range of transition temperatures, which are achieved by methods involving infrared, microwave, supercooling, chemicals and direct heat. The range of "trigger temperatures" for various smart materials means that it is possible to place the products in a heated environment where the outer elements become detached and then move on to a higher temperature zone where internal parts and sub-assemblies are dismantled.
[edit] Examples of AD fittings
Screws, rivets, ribbons, bars and clips, specially designed to facilitate AD, can be manufactured from smart materials such as SMAs and SMPs. These will trigger at a pre-determined temperature, depending on the specific application.
