electrical and electronic | LEDs
spotlights and street lamps, and customizable diffusion levels for architectural applications and retrofits in residential settings. Lexan LUX-C resins, for example, have transmission of about 91% at 1mm thickness. Polycarbonate suppliers emphasise PC’s heat
resistance advantage over PMMA. Non-reinforced grades of this material are subject to minimal deforma- tion under a light load at temperatures of up to around 135°C. PC also has higher impact strength and is more flame-retardant. Benefits of PMMA over polycarbonate include its higher light transmission (< 92%) and better UV resistance. Standard grades of polycarbonate do have a slightly
Throwing light on the LED luminaire market
LED prices are tumbling even faster than anticipated, due to overcapacity in LED chips and packages and slowing demand growth in LEDs for backlighting, helping to further drive technology transition. The green revolution in lighting is also continuing apace. In its study ‘Lighting the way: Perspectives on the global lighting market 2012’ consultant McKinsey says 2013 will be the first year that the size of the LED package market in general lighting will exceed that of backlighting. Many backlighting players are entering the general lighting market to
compensate for the anticipated decline in backlighting business caused by developments such as OLED televisions, which require no backlight. While the solid state lighting (SSL) market will enjoy 12% annual
growth rates through 2017, general lighting applications are now the largest market, measured by revenue, for packaged LEDs. Executives from consultant Strategies Unlimited reported on the 2012 market for packaged LEDs and SSL products at the recent Strategies in Light conference. They calculate packaged LED revenue hit $13.7 billion in 2012, while solid-slate lighting (SSL) revenue for lamps and luminaires combined reached $11.8 bn. There are numerous reasons that LEDs will continue on a growth
path, according to Vrinda Bhandarkar at Strategies Unlimited, but most come back to efficiency. In the long term, she projects that LEDs will be the only clearly viable solution to the energy issue. Increasingly stringent guidelines in the US will result in a phase-out of halogen lamps between 2014 and 2016, she believes. Fluorescent technologies including compact fluorescent lamps (CFLs) also have a shaky future, partly due to the high prices of the rare-earths they use, partly due to the higher energy efficiency and longer lifetimes of LEDs. Many of the LED lamps we see in shops today are for retrofits into
sockets originally intended for incandescent or fluorescent lamps. But LED lighting is a disruptive technology—LEDs can be used in ways that are impossible with older technologies. It is already resulting in new form factors and new ways of thinking about light. Plastics product designers are expected to have a field day. ❙
www.mckinsey.com ❙
www.strategies-u.com
26 INJECTION WORLD | April 2013
yellow tinge, which increases as a function of the thickness of the material. Bayer has added a number of custom LED grades to its Makrolon family, with a range of viscosities, colour and UV resistance. The light transmission of new grades is higher than that of stand- ard grades, and it falls only slightly at higher thick- nesses. Even after being exposed to white LED light for long periods, their optical properties remain virtually undiminished.
Layered manufacturing Bayer says it is carrying out comprehensive research work on making LED lenses from polycarbonate. A technology cell at its Technical Service Center in Leverkusen includes an injection moulding machine, a mould with an intricate system of temperature control, and an optical test stand used to test the quality of the injected lenses. The tests centre on collimator lenses, which produce
concentrated beams, often with free-form surfaces and non-symmetrical geometries that make it possible to focus LED light with a single lens. As a result, they not only save space but are also lighter than conventional lens systems. One special feature of lenses with free-form surfaces
is that they have areas with thick walls and some big differences in wall thickness. Very long cycle times, sometimes up to 20 minutes, are needed to achieve high optical quality with low stress and high dimensional accuracy during injection moulding or injection com- pression, and this is often not cost efficient. BMS uses multi-layer injection moulding combined with dynamic mould temperature control. The component is gradually assembled in several layers using injection moulding with an index plate mould. This results in far shorter cooling and thus cycle times. Three-layer injection moulding can cut cooling times by around 45%. Multi-layer injection moulding also results in much
better component quality. There are far fewer shrink- age-related sink marks, for example, because a greater
www.injectionworld.com
PHOTO: DSM
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