Fibre lasers - not all the same

Fibre lasers got their first big public push at last year's EuroBLECH show in October (see http://bit.ly/dJwqCI), with two UK launches made in March - by Trumpf and Bystronic, with Amada launching its machine onto the market this month (May). In brief, fibre laser profilers cut thin material faster than CO2 machines; cost less to run, both electricity and consumables; and can cut reflective materials, due to a shorter wavelength of emitted light. But a point to note is that while the generic term for this new breed of laser profiler is fibre laser (or fiber, depending upon your preference), there is potential for misunderstanding from the outset. Trumpf's latest 2D profiling machine, the Trulaser 5030 Fiber, does not use a fibre laser source, but instead employs the company's established TruDisk technology, a Yb:YAG laser (ytterbium:yttrium-aluminium garnet). Established mostly in welding that is, because its use for laser profiling dates only from 2008. The laser beam from the TruDisk 3001 unit used with the TruLaser 5030 Fiber is, however, delivered to the point of use via glass fibre, which is not novel for the company, it having employed this with Nd:YAG laser profiling machines in previous times (see later). Image: Trumpf's TruLaser Fiber WHAT'S IN A NAME? So Trumpf is using the 'Fiber' nomenclature for all of its machines using solid-state laser sources that employ fibre optic cable as the beam delivery medium, explains Nick Damjanovic, national sales manager, machines. Trumpf UK managing director Hartmut Pannen highlights that the company has two CO2 lasers and four solid-state laser sources, so putting the laser source on its machines would make it "all too complicated" for users. "We just distinguish between the optical path," he offers. But Trumpf is unlike other laser profiler manufacturers in that it not only manufactures its own laser sources, but also makes a wide variety of laser sources, including solid-state types of which fibre lasers are one type (see online article summary of laser types and basic differences). No other companies supplying fibre laser machines makes their own laser sources, Mr Damjanovic emphasises. And having looked at all of its laser sources, he says Trumpf chose its TruDisk technology for fast, economic thin sheet cutting. Trumpf's TruDisk technology is, incidentally, unique - no-one else in the world manufactures similar design lasers, it is claimed. Most of the other players in the fibre laser field employ IPG's fibre lasers as their source (www.ipgphotonics.com), although other sources exist, according to Bystronic and which says it uses IPG plus others' sources. Fibre lasers see the laser generated within glass fibre itself, the glass fibre being doped with ytterbium in IPG's case, before being released into another, standard glass fibre that takes it to the point of use. Amada has worked with American company JDSU for its fibre laser machine, incidentally (see later). SOLID HISTORY To underline its credentials, Trumpf explains that it originally introduced a solid-state laser in 1995, employing Nd:YAG technology, and sold 47 of them, says Mr Damjanovic. A twin-head version followed, but no further developments in the solid-state area occurred till 2008, with the TruLaser 7040 Fiber, a twin-head machine fitted with 6 kW TruDisk technology able to employ 2 by 3 kW or 1 by 6 kW output. TruDisk technology was then fitted to a combination punch/laser machine, the TruMatic 3000 Fiber in 2009. In April last year, the TruLaser 5030 Fiber was launched as a concept machine with 3 kW TruDisk technology, and the reaction prompted its release. Image: Trumpf has history with fibre-delivered laser technology For the machine, which can handle sheets of 3,000 mm by 1,500 mm, Trumpf says that on thin sheets up to 4 mm, part production costs can be reduced by up to 20% when comparing its 3 kW TruDisk laser to a 5 kW CO2 laser. In fusion cutting of stainless steel up to 4 mm thick (N2 assist gas), the TruLaser Fiber achieves feed rates up to three times faster than on its CO2 counterpart. This reduces the 'table time' by up to 45% and decreases the cost per part significantly. And in addition to construction steel, stainless steel and aluminium, the TruLaser 5030 Fiber also cuts non-ferrous metals such as copper and brass, due to its lower wavelength laser – about 1/10th that of CO2, but not quite the same as IPG's or Amada/JDSU's . When cutting with O2 as the laser assist gas on materials up to 4 mm thick, there is little advantage in speed, but piece part cost is lower, due to lower power and other running costs, says Trumpf. If companies are cutting with CO2 laser and O2 as the laser assist gas, then a switch to the TruLaser 5030 Fiber and a move to nitrogen will deliver faster production and better quality at lower cost, even though nitrogen is more expensive than oxygen, the company adds. Image: Fibre versus CO2 with various gases Image: Similar maximum sheet thicknesses – but burring in fusion cutting restricts fibre to thin sheetmetal Image: Comparable quality with a 5kW CO2 laser. Only thicker material shows greater edge roughness, due to the lower laser power Image: Fusion cutting (N2) - High quality in thin sheets: Less roughness and no burring. Burring increases from about 4 mm sheet thickness onward The TruLaser 5030 does cut mild steel up to 20 mm thick and stainless steel and aluminium up to 15 mm thick (the latter being better than 5 kW CO2, in fact). Above 4 mm thickness, if oxygen is the assist gas, there's little difference in quality, but if nitrogen is used, burring will occur. High speed plasma cutting of aluminium using oxygen with the new machine is also possible, but the technology is still being perfected. Cutting at 60 m/min on 1 mm thick material is claimed, however, making it 58% faster than CO2 cutting. Apart from performance, reduced power requirements, no laser gases, no mirrors, single head technology and reduced maintenance demands are also benefits of Trumpf's technology (see box item for more machine detail). The electricity consumption is dramatically reduced, in fact. Trumpf says that versus a 5 kW CO2 laser, there's a 60% reduction in power drawn by the machine; 45% versus a 3 kW CO2 unit. Image: Fibre lasers are energy efficient Seven of these machines have now been ordered by UK manufacturers, nearly all by subcontractors, including Lasershape, Beeston, Nottingham, which has ordered two (see online article). But since EuoBLECH, the company has sold 45 units, which it claims, makes it the world market leader in this area of laser profiling. But the technology is complementary to CO2, not a replacement, says Trumpf, at least not currently. Yet for those companies with multiple laser profiling machines, the choice to go for this new technology next time round is probably easily. BYSTRONIC'S TECHNOLOGY Swiss company Bystronic unveiled its 2D BySprint Fiber 3015 at In-House events in March. The company is coy about its laser source, revealing that one of its laser partners is IPG, but that it uses others, too. However, as far as the customer is concerned, the machine and laser is a "Bystronic package", says the company's Johan Elster, president, market division NAFTA and Europe North. Unveiled to a UK audience just one week after Trumpf's event, the BySprint Fiber 3015 is a 2 kW system, with a cutting area of 3,048 by 1,524 mm. The advantages are again with thin sheet up to 4 mm, but the machine can cut material up to 12 mm thick. Bystronic's UK managing director, David Larcombe, underlined that there is no benefit in having a higher power laser source, as cost rises faster than related performance above the 2 kW level. Image: The BySprint Fiber 3015 The company provided a running presentation at the event to highlight its technology's benefits (see video below). For materials from 1 to 4 mm thick, cutting with nitrogen sees the BySprint Fiber 3015 cut faster than CO2 and deliver equivalent quality. From 4 to 20 mm, CO2 is faster and CO2 quality better. Across all thicknesses, when cutting with oxygen as the assist gas, speed and quality are equal, but cost per part is lower for a CO2 laser. As for part cost, for 1 mm stainless steel and parts with simple contours, speed is faster and cost per part lower for the fibre technology versus both a 3.3 or 4.4 kW CO2 laser, says the company. For parts with complex contours, the speed benefit is not so high, while cost per part is only marginally less than with a 4.4 kW CO2 laser. The same fibre laser general benefits apply again, so no lenses, no laser gases etc, while machine electricity consumption is said to be 50% to 66% lower than CO2 machines. Bystronic has sold 10 of its BySprint Fiber 3015's since EuroBlech, with most going to OEMs and sold with automation. Many companies that initially thought that fibre looked like the answer ultimately went for CO2, reports Mr Elster, due to its greater flexibility. Bystronic expects OEMs to favour the technology more strongly than subcontractors. A point made by Trumpf, but refuted by Bystronic, is the issue of back reflection of laser light from shiny materials. Trumpf says that its TruDisk laser can absorb full power back reflection without a problem, but that fibre lasers experience issues where the laser delivery fibre is connected to the smaller diameter fibre laser source, with the joint physically blowing. Bystronic's Mr Elster says there is no problem for its technology, however, adding that the joint is more susceptible to mechanical damage than it is to laser back reflection. AMADA'S 4 KW LAUNCH Amada is about to launch its 2D machine, the FOL3015NT fibre laser, with 3,070 by 1,550 mm capcity, but the company stands alone in offering a 4 kW fibre laser source. The Japanese sheet metalworking technology specialist collaborated with US-headquartered laser and optics firm JDSU (www.jdsu.com) to develop the laser source. In fact, the pair have just announced they are to co-operate on the development of a second generation of high power fibre lasers even as the first generation is being launched. Image: Amada launched its 4 kW fibre laser last month (May) According to the machine specification, it offers faster cutting of thin material (2 to 3 times that of a comparable 4 kW CO2 laser) and, critically, superior speed and edge quality in material thicknesses up 16 mm (mild steel), when compared to other fibre laser systems. Examples of the 4 kW fibre laser's speed versus a 4 kW CO2 laser include: 1 mm thick aluminium - 55 m/sec versus just over 15 m/min; 2 mm stainless steel - 16 m/min versus 6 m/min; 6 mm thick titanium – 5 m/min versus 2 m/min; and 3 mm thick brass – 8 m/min versus 2 m/min. A massive 70% electricity saving is claimed by Amada for its machine versus a 4 kW CO2 machine, while JDSU's president and CEO, Tom Waechter, also highlights titanium cutting at high speed as one of the system's virtues. Other companies offering fibre lasers include Salvagnini, tube cutting specialist BLM Adige and Prima Industrie. Italian sheet metal specialist Salvagnini has two models of fibre laser, both purpose-designed for the technology and so employing a lightweight carriage and redesigned cutting head to improve the dynamics to improve the speed of processing of thinner material. The two models are the L3 and the L5, the first boasts 3 G acceleration, the latter 5 G. The 5 G model employs an additional two axes in the laser head (compass system) to move the head short distances at great speed. Image: Salvagnini's L3, offered as a 2 or 3 kW system, with automation a possibility Both machines are purpose-designed for fibre laser, unlike the initial L1XE, which was initially a CO2 machine that saw a fibre laser fitted. Salvagnini UK's sales manager, Steve Williams, says that the company isn't pushing CO2 any more, in fact. The company has also added a 3 kW source to its existing 2 kW unit, both of them IPG units. This higher powered system can cut mild steel up to 20 mm thick, and also competes with 4 kW CO2 in the 3-6 mm thickness range. Salvagnini has installed 100-plus fibre lasers over a 1 ½ to 2 year period, reports Mr Williams, while here in the UK there are now two UK installations, with an order for a 3 kW L3 also having just been taken. The first UK installation was at Altex Engineering (see box 4 for details), an L1XE, with another L1XE installed at Kent Metal, Ashford. Tube cutting specialist BLM Groups LT Fiber machine, again with an IPG fibre laser source, 2 kW, can process copper, brass, stainless steel, aluminium, steel tube of maximum wall thicknesses of 3, 5, 5, 6 and 8 mm, respectively. Image: BLM is using fibre lasers for tube processing Prima Industrie offers a 2 kW fibre laser with its 2D Synchrono machine, 3, 000 by 1,500 mm capacity. It is already a very fast design employing parallel kinematics to move the laser head independently of the traditional linear machine axes. The 100 m/min - 0.8 G performance of the main machine axes is outperformed by the 150 m/min – 6 G capabilities of the U and V axes, but which are restricted to 100 mm of travel. Prima also fits fibre laser technology to its 3D Rapido machine, 4,080 by 1,530 by 765 mm in X, Y and Z. Box items Different lasers - what's the difference? Trumpf TruLaser 5030 Fiber in more detail Subcontractor buys two Trumpf fibre lasers Fibre laser for Altex Precision laser cutting and welding, with Trumpf fibre laser Box item 1 Different lasers - what's the difference? [] CO2 lasers see electricity passed through a gas, CO2, to produce light. These machines require a large supply of lasing gas, while to get the beam from the resonator to the metal takes careful alignment and maintenance of mirrors. They draw a lot of power and produce extremely hot gas that requires cooling, which is why the CO2 laser's wall plug efficiency—or the optical power from electricity consumed—is only 10 to 12%. Wavelength of emitted light is 10,600 nanometres (nm). [] Nd:YAG (neodymium:yttrium-aluminum garnet) solid-state lasers see a solid rod of material 'pumped' with light from flash lamps or diodes. No gas or mirrors are required and the beam can be delivered via fibre optic, but efficiency is low at 3-4% for flash lamps, higher for diode-pumped, 10 -20%. Emitted light wavelength is infrared light at 1,064 nm. [] Trumpf TruDisk uses a small Yb:YAG (ytterbium: yttrium-aluminum garnet) disc pumped via diodes and produces light with a 1,030 nm wavelength, which is delivered via glass fibre to the point of use. TruDisk laser source efficiency is 25%, says the company. [] Fibre lasers employ glass fibre doped with ytterbium, in the case of IPG, to generate the laser and employ diodes to pump it. The laser is then transferred via another glass fibre to the point of use. Wavelength is about 1,070 nm, and IPG says its fibre lasers offer "greater than 30% wall plug efficiency". [] Details about the JDSU/Amada fibre laser are scarce. In an Amada release in July 2010, the critical element seems to be that there is a "newly developed oscillator" which " differs from those produced by other companies in that its optical engine adopts [a] method of directly oscillating [a] Yb (ytterbium)-doped active fibre by laser diode (LD) pumping" with the "amplified beam guided seamlessly through fiber". The wavelength of emitted light is 1, 080 nm and efficiency of the system is "comparable to the wall-plug efficiency of the IPG laser". Amada has invested almost £11 million "in the development of [a] fibre laser oscillator". The company will manufacture its new machine at its Fujinomiya factory, investing a further £14.5 million there to achieve this. Fujinomiya city, Shizuoka prefecture, is over 100 miles south west of Tokyo. Box item 2 Trumpf TruLaser 5030 Fiber in more detail The TruLaser 5030 Fiber is a 2D laser cutting system that can process sheets of up to 3,000 mm by 1,500 mm. Image: Trumpf's TruLaser Fiber As the complex beam guidance system of the CO2 machine is substituted by fibre guidance on this machine, Trumpf has been able to accommodate new construction ideas, with the result that the footprint has been reduced by a substantial 20%. In addition, the solid state laser and cooling units can be sited up to 50 m away from the machine. The connected power for the machine is where a drastic difference can be noted. Electrical power consumption is 18-29 kW, with a connected load of 40 kVA for TruLaser 5030 Fiber, while for a 5 kW CO2 laser machine, the figures are 72 kW and 105 kVA respectively. And at 100% laser power, versus a 3 kW CO2 laser, power consumption s 45% less; versus a 5 kW laser, it's 60% less. The cutting head is completely sealed, with only the nozzle and a protective glass lens at the bottom of the head consumable items. Automatic nozzle change is available, allowing automatic switching between materials and, thus, unmanned running. Box item 3 Subcontractor buys two Trumpf fibre lasers Subcontractor Lasershape, Beeston, Nottingham, is the first UK company to buy two TruLaser 5030 Fiber laser profilers. Now in its 23rd year, the company has four CO2 laser machines, three Bystronic and one Mazak, as well as water jet and press brake technology. Managing director Tim Leam explains that the company had already looked at fibre machines, as the company had a power restriction and this technology was the only one that would allow him to add more machinery. But, following a visit to EuroBlech last year, he says he was unconvinced by those companies offering third party laser sources, while he felt the technology looked "a little rushed to market". It looked "risky", especially as he was after two machines, so with the amount of money to be invested, risk was not attractive. "I decided to buy another factory which could take five or six CO2 machines, but then I came across Trumpf, which took all the negatives away. The laser source is proven and I don't like having two suppliers on a machine, as it can cause problems when there's a breakdown." Indeed, he has experienced just such problems with previous machines. And breakdowns are something that the company can't accept. It runs 24/7, so any delays mean that it can't catch up any time lost. The company has two in-house maintenance engineers and "reduced maintenance on the Trumpfs was a big factor for me", says Mr Leam. For example, the company spends £50,000-60,000/year on lenses for its CO2 machines, while operator training for the new machines will also be lower. The company has enough material to keep the two machines fully occupied and so will benefit from much faster throughput for these parts now, while thicker material will be processed, on occasion. "I was disappointed with cut quality on others' fibre laser machines, compared to our CO2 machines, but Trumpf's edge quality was better than our CO2 machines, in fact," Mr Leam adds. Copper, which the company cuts using water jet at the moment, will also be transferred to the TruLaser 5030 Fiber, with tremendous speed increases. Interestingly, Mr Leam was able to benefit from a £100,000 Carbon Trust four-year, interest-free loan to support the purchase of these new, energy-efficient machines. Box item 4 Fibre laser for Altex The UK's first Salvagnini L1Xe fibre laser profiling centre has been installed at the headquarters of Altex Engineering in Calne, Wiltshire. Altex benchmarked the L1Xe against a number of competitor machines, but nothing could match the machine's overall performance, with it proving five times faster than the eight-year-old 3 kW laser cutter it replaced. Image: Nothing could match the LX1E's overall performance The machine processes steel up to 18 mm thick, stainless steel up to 10 mm and aluminium up to 8 mm. Due to the wavelength of the fibre laser, it is also possible to cut highly reflective materials, such as copper and brass, up to 5 mm thick - something not achievable using more conventional CO2 laser technology. General laser profiling tolerances at Altex are 0.2 mm, which was about the limit of the company's previous laser cutter, however, the Salvagnini L1Xe has a kerf of 0.07 mm, making such tolerances more easily held. Optical fibre is used on the L1Xe to both generate the beam inside the electronic source and transport the beam from the source to the machine. The dense beam that is produced does not require high power levels to function, even when cutting thick materials. Power consumption is up to 75% than the previous profiling machine, and managing director Adrian Brewer anticipates electricity savings in the region of £500 per month. Altex is generating further savings through an in-house nitrogen generating plant that was installed last year. At a cost of £70,000, the plant is saving about £22,000 a year on cylinder delivery and consumption, so it is expected to pay for itself in just over three years. The added benefit of using nitrogen as an assist gas is that it doesn't oxidise the edge in the way that oxygen does. Using oxygen means that sheet metal parts need to be wire-brushed after laser cutting to remove the carbon layer before painting. Using nitrogen eliminates this need for edge cleaning. Box item 5 Precision laser cutting and welding, with Trumpf fibre laser Another new introduction at Trumpf's In-Tech 2011 event was the TruLaser Cell 3010 with TruFiber 400 laser source (a fibre laser). This is described as a fully controlled CNC laser processing system that "opens up completely new possibilities where conventional cutting methods such as milling or wire EDM reach their limits". Image: The TruLaser Cell 3010 with TruFiber 400 laser source (a fibre laser) This machine can be specified with a choice of beam sources to suit the application, but at In-Tech the TruLaser 3010 is shown with a TruFiber 400 W diode-pumped solid-state laser. Characteristic of this laser is its high process speed, narrow weld seams and small cutting kerfs, typically less than 100 µm wide. It is particularly suited to the precision processing of medical and electronics parts. Depending on the imaging ratio of the focusing optics, the TruFiber can achieve a focus diameter of as small as 50 µm. The resulting high power density at the workpiece translates to high processing speed. An optional Cutassist module supports the cutting process by automatically optimising the laser parameters to the cutting speed. This ensures the best cut quality and maximum productivity. Trumpf's TruTops software provides dedicated CADCAM for 3D processing. A new development is the dynamic level programming feature that enables the TruLaser Cell to be programmed block by block, according to the machining contour, so the user can choose whether speed or precision takes priority in the machining process. Various settings tune the laser to the processing task. For no-warp welding applications, multiple focus settings can be selected. Further options include pivotable focusing that enable different weld angles to be precisely set and a rotary axis for simple processing of rotationally symmetrical workpieces. Custom-made fixtures may also be specified. In addition, the increased dynamics on all the machine axes, as well as the higher speed of the Z-axis, reduce machining times. As a result, the economic potential of the energy efficient fibre laser can be optimally exploited. First published in Machinery, May 2011