A Bonding Experience
- March 29, 2019
Fiber laser welding technology is gaining traction because of speed, efficiency and decreased post processing
Fiber lasers are clearly here to stay and trending as the must-have technology for their extreme flexibility with a myriad of processes and well-known energy efficiency gains. As a welding technology option, it resolves issues with highly reflective and difficult materials.
Fiber laser technology has become much more affordable and job shops can achieve a near perfect quality weld, faster cycle times, and a significant reduction of post processing.
“People are realizing they can’t get quality welders and they’re spending a lot of time on post processing,” says Dan Belz, FLW product manager for Amada.
“Just like how the industry has been moving more toward automation over the past two years, now they’re starting to move towards robotic welding and fiber laser welding. The finish is perfect and you don’t have to post process—no grinding, no sanding. That’s a huge savings on not only abrasives and those types of materials, but also on labour.”
Masoud Harooni, product manager for TRUMPF’s laser welding group, says laser welding is not only faster and delivers a pristine quality compared to traditional welding, but it has a lot of advantages in terms of post processes for particular parts that need a good physical quality, such as appliance or food industry products that are normally stainless steel.
“If you do traditional welding, you need to spend a lot of time grinding the weld seams to make them aesthetic for the next process. We had a customer that was producing parts that took 45 minutes—20 minutes of welding, 25 minutes of grinding. But using laser welding technology, it took them less than four minutes to make the part with superior finish quality that requires no post process. Also, the heat input from laser welding to the part is much less compared to traditional MIG or TIG, so distortion is not an issue. This means less susceptibility to metallurgical defects such as cracking and porosity. This makes laser welding a very useful method to weld thinner materials such as 26 gauge.”
This shift in welding technology is about reeducation, according to Belz. “What companies have been designing for the past 40 years has been based on putting materials together, whether it’s MIG or TIG, grinding it off and dealing with big sloppy gaps. With fiber laser welding, you’re not redesigning from scratch, you’re just tweaking your process,” he says. “With a MIG process, you’re layering on a lot of material. You can cover a lot of sins that way.”
Fiber lasers have the advantage over traditional welding processes in that with lasers, the melt pool does not have the same dynamics of arc welding such as electromagnetic fields and arc forces, which affect stability and repetability. With fiber lasers, it’s more “point and shoot” process. “The laser light has a repeatable/consistent output,” says JJ Sixsmith, general manager for Liburdi Automation Inc.
The fiber laser process is also faster in terms of cooling and weld solidification rates. With traditional welding techniques, the operator isn’t able to offload a part without gloves, but you also want those parts to cool before touching them.
Amada offers two fiber laser welding models—its first generation FLW 4000 and FLW 3000, which was launched about a year ago. “With the FLW 3000, we incorporated our ENSIS technology that we use with our laser cutting. What customers are thrilled by is the quality of the welds,” says Belz. “Depending on what they’re trying to weld, material thickness and type, we have developed techniques that can be applied. We have a great wire feed system and we’ve been doing some work with exotic metals like titanium. We’ve been fusion welding titanium and also wire feeding titanium, and we’ve had phenomenal results.”
Amada’s ENSIS technology allows the mode of the beam to be changed. “From a straight beam, we get a nice deep penetration on thicker materials. A wider beam will help bridge some bigger gaps. And a split beam really helps with the wire feed and getting that wire down and having a nice feed on that. With that, there’s very little post processing that you have to do.”
TRUMPF’s fiber laser technology, TruDisk, is a high power, solid state laser source designed for welding. “This technology helps customers for a more reliable process as well as very low maintenance” says Harooni.
TRUMPF’s offline programming software allows the customer to program the part by having a 3D model. This will prevent interruptions during production.
Over the years, there has been a lot of work done on laser welding technology and techniques for working with highly reflective materials such as titanium, certain alloys and aluminum. Ten years ago, such reflective materials would cause older lasers to fault out due to back reflection.
Liburdi builds custom closed loop welding systems and mainly services the aerospace and medical industries. It integrates fiber lasers into five and eight axis gantry systems. “Our fiber lasers and the work we do is all completed on typically unique, difficult to weld alloys and applications,” says Sixsmith. “Alloys used in turbine engine components are highly affected by heat inputs and effective cooling rates. If the substrate or filler material heats up too much and cools too quickly, you can have solidification cracking. The laser allows us to finesse and manage the heat input with a high level of control so that we know consistently what our parameter values are. Because of the fact that we use a closed loop welding system, we’re monitoring our laser outputs and can control wattage to input a precise amount of heat into these components.”
Liburdi employs closed loop sensors to monitor the weld pools. It has four to five product lines that are tailored to a customer’s process and driven by an application specific philosophy.
“It’s easier to automate a fiber laser, you calibrate the units to the machine and receive a repeatable output. The fiber laser has the ability to having the laser do autogenous welding, as well as the flexibility to use filler materials such as laser wire and laser powder,” says Sixsmith. “Liburdi uses fiber lasers with both powder and wire filler with crack sensitive alloys and difficult to reach areas. So if we have to laser clad a specific part, that process works well.”
Sixsmith says that Liburdi uses fiber laser welding somewhat differently than other companies.
“A lot of companies in a variety of industries use fiber lasers for restoring simple geometries, but Liburdi uses the process for difficult geometries that typically come along with aerospace components.”
Belz says that the most difficult material Amada has welded is the 6000 series aluminum.
“It’s a soft aluminum that’s used for extrusions. It’s a nightmare to weld even in ideal conditions because it doesn’t even like to be welded to itself. Even laser welding didn’t really help that process, but once we were able to figure it out, it was huge that we could do it. You have to use 5000 or 4000 series as filler. It’s about getting the right mix of material.”
One of Amada’s customers used 6000 and 5000 series aluminum but didn’t want to use filler. If it were not welded properly there would be micro-cracks in the material. “It was daunting. We have what’s called a wobble lens/weave lens to agitate and mix the material,” says Belz. “How it works is while you’re running your optics with your focus lens, another lens moves into that position when you use the weave. It has a motor attached to it that wobbles it and forces the beam to move or rotate a bit bigger. Or if you’re fusion welding and joining two pieces of material, you’re bringing material from both sides to fill that gap. We’ve adapted this technique to the 6000 series aluminum.”
If you’re attempting to fusion weld 18 or 16 gauge steel, for example, there’s no margin for error. That’s why fixturing is critical, especially when you’re using automation, according to Belz. But on the flip side, Amada has some customers that have become so proficient with the technology, that they get their two materials close and use the FLW’s teaching assist system (TAS)—a CCD camera that helps compensate for any deviation from the weld path—to adjust the weld line on the fly.
“It’s amazing how some have adapted to the technology and use it in ways we didn’t think you’d want to use it.”
Laser welding is also capable of processing multiple configurations and joint integrations. And the speed and quality is impressive.
Belz points out that a really good welder could probably do 15 to 20 inches a minute. Some can go faster, but you’re not going to find those welders in a manufacturing facility. With today’s fiber laser welding, a typical weld speed would be about 40 inches per minute.
Considering all of these process improvements, and the fact that there is a rapidly depleting pool of skilled welders or next generation welders, it’s no surprise that automated fiber laser welding technology is quickly gaining traction. SMT