applications Materials processing
Where a high peak power is required, ipg’s quasi- continuous wave fi bre laser aims to replace pulsed nd:Yag lasers
of holes are drilled into them, through which cooling air fl ows. ‘We’ve been using our lasers to drill holes through both the TBC and the alloy. It’s a challenging thing to achieve because, although the alloy is quite easy to drill, the TBC itself is a ceramic and tends to crack when heated. It needs a combination of designing a good laser and also having a very sophisticated software system to control the laser input for each pulse.’ Lamp-pumped lasers may seem a little old fashioned, but such percussion drilling applications require a pulsed laser with high peak power, and lamp-pumped Nd:YAG lasers remain the most common way of achieving this. ‘When we’re drilling we are trying to evaporate the material rather than melting it, and so we need that high peak power,’ explains Naeem. Bill Shiner, VP of marketing at fi bre laser specialist IPG Photonics, reveals that the company’s recently introduced quasi-continuous wave (QCW) laser was developed specifi cally to compete with lamp-pumped pulsed lasers in these high peak power applications. ‘Typically these lasers might offer 3kW peak pulsed power, but their average power is low, because they’re pulsed. Prior to the QCW laser, if you required a laser with a 3kW peak power I would have to sell you a 3kW fi bre laser, but it would be constantly at 3kW, and it would certainly be more expensive than a lamp-pumped equivalent.’ The company’s new QCW lasers change this, Shiner says, by offering high peak and low average power. ‘For example, a QCW fi bre laser with a peak power of 1.5kW has an average power of just 250W. We’ve also reached a price point at which we can actively compete with a lamp-pumped pulsed YAG laser, with the advantage of attractive pricing and all the benefi ts of fi bre lasers.’
Among the most important of these benefi ts, he says, is effi ciency: ‘Fibre lasers offer a high wall-plug effi ciency of up to 30 per cent, whereas this could be as low as 2 to 3 per cent on lamp- pumped Nd:YAG lasers.’ Greater effi ciency means the laser itself can be seen as a more green solution, but Shiner adds that environmental considerations are a signifi cant driving force
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across the whole range of materials processing applications: ‘One area that is generating a lot of business for us is the so-called energy sector, which gets us into welding automotive batteries, working on wind tower projects, and even being involved in the automotive switch to high strength steel.’ The automotive industry is beginning a transition from mild steels to high strength steels in cars, as less steel can be used for a given component, minimising weight and creating more effi cient vehicles. ‘We’ve seen a lot of demand for cutting this material at very high speed, and the only other way to do it [apart from high-power lasers] is to use plasma cutting. We’ve enjoyed an increase in business as the automotive industry has been ramping up to switch over to these high strength steels, which are not as easy to cut as the materials they were using before.’
Happy shopping
High peak power is also a parameter that the latest generation of sealed CO2
lasers from
Coherent also offers. The company has recently pushed the power of its slab-format lasers to more than 1kW, allowing the company to compete with lamp-pumped lasers. ‘Our 150W Diamond E-Series laser puts out 375W of peak power, and our 400W laser puts out 1kW of peak power, and the 1kw laser puts out greater than 2.5kW of peak power,’ says Frank Gaebler, senior product marketing manager for CO2
to a certain extent, laser technology is the easy bit
lasers at Coherent. The high peak power offered by the slab architecture sealed lasers leads to
performance advantages over fl owing-gas CO2 lasers, particularly in metal cutting applications: ‘High peak power allows more effi cient coupling of light into refl ective materials,’ says Gaebler. ‘The cutting speed of our 1kW [sealed] laser is equivalent to that of a 2kW conventional laser.’ According to Gaebler, CO2
lasers are a
superior product to fi bre lasers for many applications, particularly in job shops where steels of more than 4mm thickness may need to be cut. ‘The coupling effi ciency of fi bre lasers is, in theory better than that of CO2
lasers, and
they’re particularly good for cutting thinner metal materials, but it’s not a cut and dried comparison,’ he says. CO2
lasers offer the job
shop user versatility, particularly where good cut speed and quality are required in thick steels, or where organic (wood, polymer) materials may also need to be processed.
Performance without
compromises
20 CELEBRATING 20th
YEARS anniversary
2011 marks the
of InfraTec’s designing and manufacturing of the highest qua lity pyroelectric detectors in the world market for use in:
gas analysers radiometers spectrometers
InfraTec GmbH headquarters
Dresden - GERMANY
InfraTec - Infrared Sensor and Measurement Technology Ltd. Chesterfield - UK
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