Laser welding: Amplifying efficiencies

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Fiber laser welding technology has quickly advanced as the must have solution for high volume, low mix demands. Is it right for your shop?

By Noelle Stapinsky

The automotive industry is undoubtedly a trailblazer when it comes to manufacturing automation, and as an early adopter of laser technology—specifically laser welding—it has helped drive innovation for this automated welding solution. With the current push towards electric vehicles, such technology is truly in the spotlight as more manufacturers are focused on achieving faster, stronger welds, low distortion and reduced post processing. And with laser welding gaining wider adaptation and utilization in fabrication and manufacturing, constant advancements are driving costs down and making it more accessible.

From large segment manufacturing such as ship building to automotive transmission parts and structural components to pacemakers, laser welding solutions on today’s market have proven to deliver high quality results for long, deep seam welds, as well as fine spot welds as small as one millimeter in diameter. And the versatility of this technology is impressive. Not only can it weld a wide variety of steels and alloys, but it also offers soldering processes, plastic welding solutions and welds of highly reflective materials such as copper. What’s more is that laser welding travel speeds can be up to ten times faster than TIG and five times faster than MIG in various applications.

As the technology has evolved, suppliers are offering a range of solutions that can be optimized and dialed in to meet customer specification. And some are also offering hybrid technology that automates and mixes traditional welding processes with laser technology.

Light tight solutions

For the sheet metal industry, Masoud Harooni, TRUMPF’s laser welding product manager, recommends laser welding technology. The TruLaser Weld 5000 can have a high power laser and a variety of modular positioners for processing mid-size to larger components. One of the main benefits of this cell is that it has an automatic rotary table for processing larger runs. TruLaser Weld 5000 series is TRUMPF’s turnkey solution that can fit OEMs and job shops. One of the benefits or laser welding is that it can have structural welds (deep penetration), visible welds (heat conduction), and laser-assisted with wire ((FusionLine) within one program.

Of course, there are many other TruLaser cells offered in TRUMPF’s line up depending on what kind of processes you wish to achieve. But one of the major considerations Harooni suggests for customers looking at investing in laser welding technology is the fixturing that will be required. “If you have high variation parts and might need 50 different fixtures, for example, laser welding doesn’t make sense. But if there’s a reasonable amount of fixtures, such as 10, needed for the lots that you run, then it makes sense for the investment. TRUMPF will investigate the customers needs and what kind of investment is needed to come up with the return on investment (ROI), which typically is within a couple of years.”

One of TRUMPF’s newest features that it has added to its laser welding cells is a zero-point clamping system. “With laser welding, we need high accuracy tooling or fixturing,” says Harooni. For shops that need different kinds of parts or batch production, fixtures will often be swapped out for a batch changeover. But when a fixture needs to be reseated in the exact location as a previous run, this can be a timely process and might require adjustments in the program.

With TRUMPF’s zero-point clamping system, there are four housings on the machine, and four highly machined pins attached to the bottom of the fixture. “So when you put these pins underneath each fixture, they will center in the housings and a pneumatic system will move the fixture into position and there would be zero variation in that placement,” says Harooni.

Having a laser cutting system is also essential for a clean, quality accurate weld. “Laser cutting is great for laser welding because of the tolerances it creates. If we cut with a plasma system, don’t even think about laser welding that material,” says Harooni. “The difference between plasma and laser cutting is equivalent to cutting a piece of paper by hand with scissors or slicing the paper with an office-style guillotine paper trimmer. Which edge would you consider to be the straightest? If we don’t have an accurate edge or the tolerances needed and you put those edges together, it’s not going to line up straight. And when placed on the fixture, it can move based on those tolerances.”

Steve Massey, Miller Electric Mfg.’s arc research and advanced process engineer, agrees, “The precision has to be higher for laser welding. You will likely be working with a machined edge, whereas with arc welding you can be dealing with a thermal cut edge. So there are some trade offs.”

When considering total joint completion rate with traditional arc versus laser, Massey says, “if you’re doing a butt joint with arc welding, you’re going to likely have a reasonable bevel on those plates. The cross-sectional area of that joint, as far as the amount of fill that you’re going to need to provide, is going to be fairly high when compared to that required for laser welding. With laser welding, depending on the thickness of the material, the bulk of that edge prep would just be a square edge and you can complete that full penetration with a much smaller joint volume.”

Make it a combo

Fronius’ LaserHybrid solution is a combination of MIG/MAG and laser welding. Designed for shipbuilding, automotive and other large-scale series production, this technology mix features deeper/narrow penetration, reduced consumption of filler materials, lower heat input, weld travel speeds of up to eight meters-per-minute, and significant improvements in gap-bridging ability.

Ivan Wright, a technician for Fronius, says, “The real beauty about the LaserHybrid is that we technically have three processes in one system. We can laser weld only, MIG weld or combine the two. Increased speeds are one of the features of process stability. And we also have great gap bridging abilities compared to conventional welding processes or a laser only process.”

Speed, reduced heat input and distortion are all vital aspects for processing high strength steels and aluminums, and a particular focus of many automotive OEMs. “Typically, what we’re seeing now—the big one—is welding aluminum. So, battery trays and aluminum type components and what’s happening now with the transition to electric vehicles, weight savings, efficiencies, etc.,” says Wright. “Post processing in terms of machining parts and things like that, you do get a certain level of distortion, which is critical for OEMs. Any reduction in handling and time savings for a facility is significant.”

“The LaserHybrid has the ability to get up to those higher speed ranges, while minimizing the heat input, which is what causes distortion in welding applications,” says Wright. “So we’re talking over three metres-per minute of travel speed on four millimetre base material to two millimetre top sheet. That’s significant. And it’s not necessarily related to cycle times and throughput, but more about the quality of the part. And then you can look at weight savings compared to a conventional MIG processes. In some scenarios, you would be using 50 per cent more filler wire than you would with the hybrid process.” 

And while Wright agrees that laser cutting and fixturing are critical for a laser only process, the hybrid system will tolerate more variance in the setup. “We can get into multi-layer welds and reduce passes and seam preparation by having the keyholing of the laser and the back filling of the MIG process.”

Laser welding is also known as a low spatter method, as parameters are set to control the density of the beam to not disrupt the weld pool. With the MIG/laser mix, Wright says, “we handle spatter in terms of a correctional parameter, whether that be arc length, control, dynamic control, and also just the process itself. We have stabilizing parameters that we can use to induce a short circuit to stabilize the arc on the MIG side, where the spatter is typically generated.”

For the LaserHybrid, Fronius also has several different head configurations: a 10kW Fillet Weld, a 4kW Twin, 4kW Ultrakompact, and a 10kW universal.

“We manufacture the welding head on the MIG/MAG side and then we can incorporate different manufacturers of lasers, such as Precitec, IPG Photonics, TRUMPF and Highyag,” adds Wright.

Speed, dialed in accuracy, the cost reduction of consumables, as well drastically decreased post processing have certainly made fiber laser welding a game changer for manufacturers with low mix, high demand part production. And as laser welding technology continues to evolve it’s quickly becoming the must have tool, especially for the automotive world, as it races to get online with demand for battery electric vehicles.

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