Laser systems play an essential role in manufacture today. Sian Harris looks at how advances in fibre technology, laser power and rapid pulse lasers have enabled improved manufacturing techniques
Test-drive a new car, check the time on your watch or tweet from your smartphone and you are likely to benefit from advances in laser technology. Advanced laser systems have become high-performance alternatives to traditional manufacturing techniques.
Take drilling, for example. Mechanical drill components become worn down over time, meaning that the size and shape of the holes being drilled can change. Drilling systems based on lasers do not have this problem. With laser-based drills, no components interact with the material being drilled – so the laser, and the size of the resulting holes, remains the same.
Another area where laser systems have brought improvements is in additive manufacture and rapid prototyping. Introducing powders into a laser beam enables products to be formed easily. Low-volume or single-item manufacture can be done quickly, with no tooling, enabling increased speed to market for low-volume products or prototypes. This also enables a broader range of materials to be used.
According to Lithuania-based Ekspla: ‘Laser micromachining is rapidly becoming the material processing technology of choice for numerous small-scale, real-world applications. New advances in diode pumped solid-state (DPSS) lasers are enabling material processes once found only in research laboratories to be incorporated into growing numbers of production lines.’
Clive Morrison, field sales engineer at Acal BFi UK, comments: ‘Lasers in manufacturing used to be novel but now have become more the norm. The laser has become a reliable tool.’
The importance of laser systems today is thanks to recent technological developments, particularly driven by the medical and electronics industries. Cutting-edge laser developments from research labs have found their way into industry and now both high-power lasers and short pulse rate lasers are pushing the boundaries of what is possible.
Gerry Jones, a product manager at Trumpf, says: ‘In recent years solid-state lasers, fibre-delivered, have brought a lower cost of ownership, higher performance data and, in some cases, better quality. The laser business at the moment is really as exciting as it’s ever been. They are coming into mainstream usage with a large uptake in industry.’
A key area of interest is in the use of short-pulse lasers. ‘The use of short-pulse lasers is very active,’ says Jones. He notes their ability to be very finely focused and controllable. Another benefit is that, because the pulses are so short and targeted, there is virtually no heat effect on the material being treated. ‘This is very interesting to a lot of people,’ he says. ‘They can be used to modify surfaces without damaging base layers, or to remove very fine coatings.’ Such developments are particularly important in the electronic industry, where there is a drive to, for example, make mobile phone screens much thinner.
Over the past three or four years there have been plenty of launches of lasers with picosecond pulses for industrial applications. Rofin’s recently-released StarPico promises a pulse duration of 12ps, pulse energy of 100μJ and an adjustable pulse repetition rate of up to 20MHz. This picosecond laser allows ‘cold’ processing of hard and brittle material and is suited to the electronics, semiconductor, precision engineering, micro and medical device industry.
Acal BFi UK is a distributor for Ekspla, which also makes high pulse rate lasers. The main applications for these lasers, says Clive Morrison of Acal, are in manufacturing photovoltaics, cutting touch screens for mobile phones and drilling for high-tech medical applications – as well as micro drilling.
According to Ekspla: ‘Picosecond lasers are capable of processing a wide range of micron scale features in metals, semiconductors, diamond, sapphire, ceramics, polymers, composites and resins, photoresists, thin films, ITO films, and glass.’
Reliability brings opportunity
Picosecond lasers are not new but their importance in industry has come thanks to recent advances in lasers and laser systems.
‘Initially the cost of ownership of picosecond lasers was phenomenally high – about a quarter of a million pounds and they weren’t as stable, which made them very difficult to commercialise,’ says Morrison. This changed, he continued, with the advent of electrooptic locking and because of advances in fibre technology.
The use of fibre to deliver laser pulses has a few advantages. One of these is being able to deliver the laser pulse to where it is needed, which has some safety benefits. It has also brought significant improvements in power consumption. This was a barrier to industrial use of such systems in the past. ‘These things used to be very large and power-hungry,’ explains Morrison. Now, he says, power consumption is coming down. Part of this is due to the use of fibre lasers. ‘No cooling is required with fibre lasers. They are nearly all air-cooled now – at least for the smaller systems – so they can now be plugged into the mains socket.’
There have also been improvements in reliability. ‘The cost of downtime is in the past,’ says Morrison. ‘When I started in lasers we would’ve been lucky to get 500 hours between breakdowns. Now you can have 10,000 to 20,000 hours between breakdowns.’
Laser manufacturers have begun to extend their range of laser systems for industrial applications to include femtosecond pulsed lasers.
Ekspla’s new LightWire series lasers promise turn-key operation, monolithic all-in-fibre design and require no maintenance. This is said to make these lasers preferable to the solid-state counterparts in industrial settings and multidisciplinary research laboratories. The range includes femtosecond and picosecond lasers at a range of average powers.
At Laser World of Photonics in Munich this year, Trumpf unveiled its first femtosecond laser – the TruMicro 5050 Femto Edition. This ultra-short pulse laser is said to be suited for industrial use and operates reliably, around the clock, without any interruptions or variations in the processing results.
Trumpf says stability of both the pulses and the power level is achieved by separating pulse generation and pulse output. The TruMicro 5050 Femto Edition promises an average power of 40 watts during 800-femtosecond pulses.
‘People are going to shorter and shorter pulses because of reduced edge-damage,’ notes Morrison. ‘Femtosecond pulses are good because they don’t generate heat. Developments have been driven by the medical and electronics industries.’
However, there are challenges, he says. ‘The generation of femtosecond pulses is still in its relative infancy. Until about two and a half years ago, femtosecond lasers were only in research labs.’
Challenges include tackling size, cost and reliability – though developments in fibre-delivered femtosecond sources have begun to address these.
Although high pulse rate lasers generally operate at low average power, because they are using intense pulses, their peak power is much higher – perhaps 10-12W. This has potential implications for laser safety. In particular, new approaches have been required because the very high pulse rates come hand in hand with a much broader wavelength range than is normally produced by lasers.
‘Femtosecond lasers have quite a wide line width so we need specialist broadband filters on eyewear,’ explains Morrison.
However, the risks are reduced because the laser is delivered through fibre. ‘Most of the cutting, welding or drilling is done in a light tight box. You still have to take reasonable caution. Reflected pulses can have very high intensities’ he continues.
For other industrial applications, laser manufacturers are also pushing to higher and higher powers.
IPG Photonics introduced what it described as a ‘new generation of kilowatt fibre lasers delivering improved performance and reliability’ at Photonics West 2013. The low-mode ytterbium fibre lasers promise lower cost per watt of laser power, operating expenses and service requirements.
The main benefits of the YLS-xxx-Y13 series are said by the company to include increased wall plug efficiency (up to 33 per cent from 28 to 30 per cent), up to two times average improvement in beam quality and an increase in the estimated mean time of uninterrupted laser operation from the current one and one-half years to greater than three years.
What’s more, the company is reported to have recently delivered a 100kW fibre laser to a Japanese customer, a move that is said to represent the highest-power industrial laser ever built.
With higher-powered lasers come additional safety considerations, an issue that UK-based Lasermet, for example, is looking to address.
‘The biggest thing is the increase in average power of high-power lasers in heavy manufacture. With these sorts of lasers containment is key,’ says Paul Tozer, managing director of the company, which provides enclosures for laser systems.
At low powers, he said, a passive guarding system (where the walls of the enclosure absorb rogue laser beams) is ideal, and the company provides these. However, as laser powers get higher – above about 5kW – this approach is no longer adequate.
The company’s Laser Jailer is an active solution based on detector tiles on the inside of the enclosure.
These tiles, which are designed to be sacrificial, are connected to the laser’s interlock control system and automatically shut down the system as soon as they detect a rogue beam.
So, what is next for lasers in manufacturing? Gerry Jones of Trumpf anticipates a drive towards even higher average powers, improved laser efficiencies and lower unit costs. ‘More cost-effective solutions broaden the markets available to us,’ he observes.
Developments in turnkey laser systems will also be important for industrial customers. This will mean that such systems will require minimum set up effort. ‘That’s what customers want and it makes a difference to the training required by operators,’ Jones explains.
As developments continue and more laser technology finds its way from the research lab to industry laser systems look to have a bright future in advanced manufacturing.