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News Item - Lasers Drive the In-line Production Systems of 21st Century Technology
Behind the commonplace consumer products such as mobile phones, MP3 players, batteries and food packaging are high volume production lines incorporating industrial lasers performing indispensible cutting, drilling and welding functions. Looking forward, green technologies such as Fuel Cells and Solar Panels rely upon lasers to perform tasks which are unachievable with conventional manufacturing techniques. These technologies too are increasingly looking to such in-line manufacturing methods to ramp-up production volumes and drive down local energy production and storage costs.
Rofin’s expertise in in-line processing began almost 30 years ago when its subsidiary, Baasel Lasertech developed high speed perforation technology to allow cigarette manufacturers to produce lower tar cigarettes. The concept is that if sufficient perforations of the right size are made around the cigarette filter paper, then smokers draw in some cooler air along with the tar-laden air that they inhale from the cigarette. This stream of cooler air encourages more of the tar vapour to be condensed inside the filter, which increases the filter’s efficiency and therefore somewhat reduces the harm such cigarettes inflict on the smoker.
From a technical point of view, Baasel’s solution was to perforate the filter paper when it was on reels several tip-lengths wide and prior to slitting. This technology has been developed and today is still in operation at sites throughout the world. The density of holes required and speed of paper on the web means that modern cigarette perforators are capable of operating at a staggering 500,000 holes per second.
About a decade ago, prepackaged salad suppliers realised that if salad bags can be perforated with the right size holes (around 70 µm) then they can breathe without drying out – more precisely, CO2, which reduces the shelf life of cut salad, can escape, whereas water vapour cannot.
More recently packaging companies have solved the classic ‘peanuts in the lap’ problem with lasers – polymer/foil packaging can be scribed to weaken the wrapper along a prescribed line without breaching to inner foil layer. Designs incorporating laser ‘easy open’ are becoming widespread as are laser produced steam vents in microwave meal packs and weakened regions in pill blister packs and drinks carton push-throughs for drinking straws As with cigarettes, the obvious way to process these packaging materials is when the polymer is in a preprinted web form, prior to being formed into a bag or wrapper. Such an in-line laser system then simply has to recognise a suitably-printed trigger whilst feeding back the real-time speed of the web. In this way the laser can do its job at very high speed and without slowing or stopping the line. It is precisely Rofin’s extensive experience of such handling technology for high speed web processing that makes it so well placed to meet the needs of upscaling production of elements of fuel cells and flexible solar cells. It is not just the right laser that needs to be selected for these tasks, but also all the other elements that combine to make such solutions work: o Reel-to-reel or in-line handling with necessary tension control and take-up rollers o Laser with fixed, moving or galvo beam delivery o Line speed sensors for closed loop on-the-fly processing o Optical sensors/vision systems for precise laser triggering o Debris exhaust and filtration o Integrated control systems o Safety Class 1 housings and interlocks Such a system will be used typically for isolation of individual solar cells on a flexible substrate by scribing a line between individual cells, sufficiently deep to electrically isolate the top conducting layer. Cells can also be uniquely coded using a laser marker as part of the system.
The conclusion is that high volume manufacturing benefits from continuous, in-line, very high speed processing – whether one is looking at perforating tipping paper in 1980 or isolating flexible photovoltaics in 2010 – the benefits of lasers are maximised if their duty cycle can be.
