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Issue 06/2016

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Consumer Electronics The

Consumer Electronics The fair PC mouse The PC mouse, a device that has revolutionised the way we use modern computers, is almost invisible on a daily basis. As a vital part of a PC system, our hands unthinkingly reach for it and without it, we feel disoriented. Its intuitive control contributes to its ubiquitous presence alongside modern PCs. It is now so common, that anyone who is not involved in the production chain may well be astonished at what is hidden beneath that neat casing, shaped to suit our hand. It looks like just another one of those electronic devices cluttering up our daily lives. Looks, however, can deceive: the complexity of the production chain and the problems, which have to be solved to fabricate a simple PC mouse are far greater than meet the eye. This is particularly the case when designing a mouse according to fair requirements, as is the aim of non-profit organisation Nager IT (Bichl, Germany), an association focussed on encouraging humane working conditions at electronics manufacturers by developing socially and environmentally sustainable electronics. Now, a junior research team (Forschernachwuchsgruppe, FNG) headed by V.-Prof. Dr.-Ing. Andrea Siebert-Raths at the Institute for Bioplastics and Biocomposites (IfBB) at the University of Applied Sciences and Arts in Hannover, Germany, working in close collaboration with Nager IT, has developed a biobased material for the fair computer mouse. Junior Research Team The FNG team is looking for new application areas for biopolymers to increase their market relevance and acceptance. Since 2012, the German Federal Ministry of Food and Agriculture (BMEL) has provided funding for the project through the Agency for Renewable Resources (FNR). To date, the main focus of the team’s work has been on the development of materials able to compete with the familiar commodity plastics present in everyday products that could better meet the demands of the customer with Figure 1 The fair PC mouse based on IfBB’s compound. Source: IfBB, Kathrin Morawietz By: Jacek Leciński, Andrea Siebert-Raths Daniela Jahn and Jessica Rutz Institute for Bioplastics and Biocomposites University of Applied Sciences and Arts, Hannover, Germany 24 bioplastics MAGAZINE [06/16] Vol. 11

Consumer Electronics respect to mechanical, thermal and processing properties. The FNG team is currently in its second funding period, during which the developed materials are to find their application. To that end, the IfBB’s partners in this project are implementing the newly developed materials in their products, with the support of the FNG researchers who are providing the technical know-how needed to effortlessly switch the production process to new biobased materials, while meeting the product’s requirements. Demanding mouse IfBB was tasked with implementing a new biobased compound and adapting an existing, aftermarket injection moulding tool (presumably designed for ABS) for sustainably sourced material in 2014. Material requirements were determined by the mechanical and thermal resistance to be delivered by the casing and the two mouse buttons, comprising the four-cavity mould. Hence, the material needed to offer adequate impact strength and a relatively low degree of stiffness, as the mouse had to be tough enough to withstand an incidental fall from a desk. A special “drop-off desk” simulation test was therefore devised. In addition, the material also had be able to withstand high temperatures, due to the possible local heating-up of printed circuit board (PCB) parts. Furthermore, Nager-IT has a policy that states that in case of failure, the electronic parts may be exchanged. Repeatable assembly and disassembly was therefore required, as was good dimensional stability (min. warping) to ensure the long-lasting functionality of the PCB, the scrolling wheel and the screw connections. Additional features, such as a pleasant touch, surface gloss or easy colouring also needed to be considered; last but not least, the compound was required to be made from at least 65 % non- genetically modified renewable resources. The challenges In many cases, modifying an existing tool for use with a biobased compound is a challenge. Knowledge of material handling alone is not sufficient to overcome the hurdles that arise. The challenge has less to do with the use of the biobased material, and more with establishing adequate processing parameters and with the correct design and maintenance of the tools. The injection moulding tool which Nager-IT obtained on the aftermarket was therefore validated first. The mould’s runner system was somewhat distinctive. Directly behind the sprue in the runner system was a small plate that functioned as a built-in valve, apparently designed to block two of four cavities, so that the mould would run on only two cavities simultaneously. The cavities differed in terms of geometry and volume, Figure 2 Modifications of the components. Source: TPK Kunststofftechnik GmbH bioplastics MAGAZINE [06/16] Vol. 11 25

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