“With great power comes great responsibility.” It’s a line everyone has heard, but few can cite. Originating from a 1962 Spider-Man comic book, it’s the advice Peter Parker’s uncle Ben imparted on him: When someone is granted enormous power, they must wield it wisely and responsibly. Regardless of its comic book roots, it’s practical advice that can be applied to a wide range of people and situations, including the use of high-power laser systems.
For anyone keeping track, power levels for fiber laser cutting and welding systems are on the rise. Systems with 20 kW or 30 kW of laser power are becoming more commonplace by the day while 50-kW machines and beyond are entering the marketplace, as well. As these higher power levels become the norm, it’s increasingly important for industry to fully understand their advantages, the responsibilities that come with them, and the need to measure and monitor their performance.
Adapt to evolve
In a nutshell, the more laser light you have, the more work you can do. Higher power lasers enable the production of higher quality parts and thicker and faster cutting, as just a few examples. In the case of shipbuilding, which requires the production of thick hulls, laser cutting historically couldn’t produce consistent cuts the way plasma cutting could. But, with the introduction of higher power levels, shipbuilders can replace their plasma systems with fiber laser technology that offers a slew of benefits.
“Over the past few decades, the application of lasers for material process has become more commonplace in industry,” says John McCauley, senior business development manager at MKS Ophir. “Compared to other cutting technologies, lasers are incredibly consistent, high-power, flexible tools that are very repeatable and reliable. As laser technology advances that becomes even more apparent.”
When fiber laser technology entered the market, it quickly turned the heads of those using CO2 laser systems based on fiber’s ability to handle a wider range of material types and its lower energy requirements, higher beam quality, more infrequent maintenance schedule, and faster cutting and welding speeds. To adopt these new, advanced technologies, however, manufacturers and fabricators would need to educate themselves to take full advantage of them. As McCauley reminds, old laser practices don’t necessarily work with these newer laser technologies and higher power levels.
“These CO₂ lasers are very easy to operate and service,” he explains. “The optics are very robust where an operator can take an optic out of the cutting head, rub it on their shirt and put it back into the machine. You simply can’t do that with fiber lasers. But, for many coming from the CO₂ world, those old practices are hard to shake.”
Therefore, ensuring high-quality laser processing is all about shedding those old habits and adapting to the new technology. Hourly workers are fortunate that these new systems are designed to be relatively easy to operate, but responsible employers understand the value of advanced training.
“A typical operator is expected to load part files, press a few buttons and, as long as everything is hunky-dory, allow the machine to do its job,” McCauley says. “But what happens when an operator gets that flashing red light on their machine? Unless they’ve had the appropriate training, they might revert to those old habits. And those are the instances when we want to talk with customers about bringing their laser knowledge to a higher level. We want them to understand how the laser light is performing and be able to do checks to accurately identify issues, such as focus shifts, that affect the performance of the laser.”
Root causes
When a laser operator doesn’t fully understand the way a machine works, it isn’t far-fetched for them to rely on outdated or ineffective remedies. McCauley has countless stories of operators cranking the power like they did with their CO₂ machines when part quality went down.
“I had an instance in an automotive plant where there were a series of laser welds on a particular component,” he says. “They started out with good welds that turned bad because there was a focus shift on the system. They were having to do a weld, pause, do a weld and pause again. Instead of finding the root cause of the issue, they wrote those pauses into their system. In doing so, they drastically reduced their cycle time and produced less parts at potentially lower quality.”
Often, performance issues are rooted in the harsh environment in which lasers operate and even create. The smallest amount of debris on a lens can create the inconsistent welds McCauley witnessed at the automotive plant.
“When you operate high-power lasers in relatively harsh working environments where there is a lot of dirt and debris but maybe not a lot of cleaning, there’s a risk of debris collecting on vital surfaces and absorbing laser light, which breaks down the component even faster and can cause a power drop,” he says. “Instead of transmitting that laser light to the process, it’s now being absorbed at the surface.
“Lasers naturally come to a point, which is where the beam’s spot size is the smallest and where it does its work,” he adds. “When you have a thermal effect, there is an optic in the system, usually the cover glass, which is closest to the process that is absorbing the laser light and essentially turning into a lens, which causes the focus spot to drift toward the laser system. When the focus spot drifts from where it’s designed to be, the spot size is growing, which affects the power density and, in turn, the performance of the laser. Overall, the success of a laser process relies on keeping the laser power and spot size consistent.”
Exacerbating the situation, today’s higher power levels translate into even harsher working environments – as more photons are being passed through machine components, they become more susceptible to the potential of greater failure and shorter lifespans. So with this understanding, maintenance and monitoring practices must also adapt.
Monitoring and measuring
For the fabricators and manufacturers that are investing in these new higher power laser systems, monitoring and measuring is at, perhaps, its most crucial stage. To find long-term success, it will be imperative to understand how the beam is behaving and the rate at which critical components deteriorate.
“If I’m pumping 70 kW of laser power into carbon steel to cut it, I need to know if I’m getting reflection or irradiation coming off of the surface of the metal,” McCauley explains. “I also need to know how that power is affecting the lens and the cover glass, considering that the cover glass most likely won’t stay intact as long as it did with a 4-kW machine. It, therefore, makes a lot of sense to apply measuring and monitoring tools to understand how the laser is performing.”
Ophir’s BeamWatch is one such tool. It allows manufacturers to see everything that’s happening with the laser beam. It measures the amount and speed of focus shifts, which ultimately informs users how to take the appropriate actions to remedy issues and achieve consistent performance. It also informs users how they must modify their maintenance routines.
Ophir’s product lines are split into two general product lines: one for power and energy measurement, helping understand the amount of light being applied to the process, and another to understand the beam profile, which includes the beam’s size, shape, geometry, Rayleigh length and divergence angle, which define the quality and consistent placement of the beam. These products can be implemented into manufacturing workflows in various ways.
“One method is at-process integrated monitoring,” McCauley says. “Think of a workcell that’s designed around a laser process that includes the laser, a robot and the tooling that brings a part in and out the process. The benefit of integrating these products directly into the cell is that it allows for frequent monitoring; the feedback is readily available and valuable. Users can bring up the laser, check its characteristics to make sure it’s at the proper power level, for instance, and then return the laser back to the system to continue on with the process.”
The second method is a standalone system, often used for troubleshooting scenarios. If a system is underperforming, the Ophir monitoring tool is temporarily brought to the system to determine whether the laser beam is behaving correctly or not.
“Both techniques collect the same information, but the integrated system is more readily available to the user,” McCauley says. “It’s designed to be left in the workcell for more frequent feedback. The second method is usually less expensive because you can use one system for several different laser operations versus one that’s dedicated and integrated. There’s some time involved with that second setup, but again, up front, it’s a little bit more affordable.”
When McCauley started at Ophir in 2009, he would put a beam profiler on a laser and for the first time, the user could see their laser and the shape of it. It was exciting to see their reactions, but he quickly understood how important it was to fully explain what they were seeing and why it mattered.
As time passes and laser technologies and power levels advance, that knowledge becomes even more critical. When users can see – and understand – the characteristics of their laser beam and how it’s affecting their work, embracing higher power levels will lead to greater success.
