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Laser Technology
Friday | 30 August, 2013 | 10:43 am

Fast fiber cutting

By Lauren Duensing

Above: The TruLaser 5030 fiber provides users with high feed rates because of its energy-efficient, fiber-guided TruDisk laser

Metal fabricator increases throughput after installing a Trumpf TruLaser 5040 fiber

August 2013 - Atlanta-based metal fabricator Tie Down Engineering is focused on quality and speed. “Whatever we can do to increase our throughput on any of our equipment, we’re going to go and make it happen,” says Sloan MacKarvich, president of the Industrial Laser Solutions Division at Tie Down Engineering.

To increase the amount of parts it could cut, the company invested in a TruLaser 5040 5,000-watt fiber from Trumpf Inc., Farmington, Conn. “I know you pay a good bit more on the front end for a fiber laser, but in the long run, it ends up being a lot less costly on a per-part basis to run a fiber laser versus a CO2 laser, depending on the part,” MacKarvich says. “We do a lot of stainless steel cutting and a lot of pregalv, and that’s not a material you can generally cut nearly as fast with a CO2 laser.”

The TruLaser 5030 and 5040 fiber lasers allow Trumpf to offer OEMs and job shops a machine that can provide impressive quality, performance and work with a wide range of materials. “We’re trying to make this machine the universal machine for laser-cutting customers,” says Brett Thompson, sales engineer of Trumpf’s Laser Products Group. 

Trumpf has experience with several variations of solid-state lasers—rod, disk and fiber. The 5030 and 5040 fiber lasers work “a bit differently from a typical fiber laser in the way we generate the beam and beam delivery,” Thompson says. “As we move into the higher-power applications where we’re dealing with bouncing protons, the best solution is using a disk because of its ability to generate more energy than a fiber.”

Thompson says increasing the power on rod lasers, like the ones Trumpf uses for microprocessing, pulse lasers and marking lasers, causes them to be less efficient dispersing the heat due to the size of the rod, which warps the beam. As a result, increasing power reduces the beam quality.

“Going with a fiber gives us the ability to improve the surface area volume ratio, and it has better cooling efficiency in high-power applications,” Thompson continues. “The problem is it’s a little bit limited in the amount of energy that the individual fiber can produce. This adds to the complexity of the system as the power increases. There is also a limitation to the amount of energy it can absorb during a back reflection. Basically, what the disk does is give us a best-of-both-worlds application. We take a rod and remove an 0.015-inch-thick sliver of that rod. And rather than have a lateral cooling profile, we lay it on a flat surface and then there is consistent cooling across the entire face, which provides consistent high-power applications without ever encountering any sort of beam reduction in quality.”

The sweet spot

Thompson says the TruLaser 5030 and 5040 fiber have a fiber optic beam delivery cable that is attached to a cutting head, which offers a full range of beam diameter adjustment. “That gives you the ability to set a beam for the smallest diameter, which is very good for thin-gauge cutting, or the largest diameter, which is very good for thick-gauge cutting, but most importantly, [you can set it for] everything in between. That allows you to rethink all you have heard about a solid-state laser and think about your applications.”

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Tie Down Engineering has four divisions that produce OEM trailer components, marine components, roofing and construction products, and manufactured housing foundation systems, in addition to its contract manufacturing division, Industrial Laser Solutions. As a result, the company manufactures a wide range of parts and has found that material from 3⁄16 inch on down is the TruLaser 5040 fiber’s “sweet spot.”

“When we started processing material on our 5040 machine, from 3⁄16 inch on down we were anywhere from two to three times the cutting speed compared with our 6,000-watt CO2 system. That was kind of eye-opening for us,” MacKarvich says. 

The company tries to route as many stainless steel, aluminum and pregalvanized parts to the TruLaser 5040 fiber as it can. In addition, “we do a lot of high-tensile cutting,” MacKarvich says. “We’ve been able to reduce our material thicknesses on some of our mild steel parts to put them in the sweet spot of the fiber laser—that 3⁄16 inch on down. We’ve actually re-engineered a lot of our products to start making use of these higher-tensile materials just so we can be in that cutting range where we’re able to get our throughput way up.”

Maintenance costs

In addition to fast cutting, “we’re also using a lot less energy for the life of the machine,” MacKarvich says. “For the life of the machine, you more than make up for the added investment costs on the front end because you’re able to generate a lot more revenue on a per-hour basis compared to a legacy high-powered CO2 machine.”

Thompson points out the resonator on the TruLaser 5030 and 5040 fiber doesn’t have any components that have to be maintained or replaced, like a CO2 laser’s mirrors. “With the machine with the disk laser, you’re going to have an air filter to replace and water to change just like any other machine, and that’s really the extent of it. That’s really what drives those operating costs down so much,” he says.

“Since the beam delivery is now going along a fiber optic cable, you’re no longer taking a beam and bouncing it off optical mirrors and down tubes and all that,” MacKarvich says. “At our worst year, we had $150,000 worth of maintenance on our CO2 lasers. That was for everything, but it still was outrageously expensive. With the fiber laser you don’t have to perform maintenance on your beam path and delivery components. No more worrying about replacing mirrors. Alignment was also another big maintenance item for us, constantly having to go and realign the optics and the mirrors on the CO2 machines. That has gone completely away. The machine will just sit there and cut parts all day long. 

“With the fiber laser, you don’t have to do gas changes anymore because there’s no longer a gas medium that you have to maintain in the laser resonator,” he continues. “On a CO2 machine, you may have to do a gas change every 10 hours or every shift. For some machines, that can be from as little as 15 minutes upward to almost a half an hour. Gas changes go away completely on a fiber laser because there’s no gas medium that you have to change out or maintain, so you’ve been able to gain that much more in production time and throughput time.”

MacKarvich says, however, there’s one caveat to cutting with the fiber laser. “You have to be using nitrogen as your assist gas in that sweet-spot range where you’re cutting at two to three times the rate of the CO2 machine. You’re using more nitrogen as a consumable, but go ahead and ask yourself this: If I had three times the throughput on my parts, is paying another $8 to $12 per hour for the extra nitrogen gas really hurting me in the long run? It’s absolutely worth it.” MM

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