A model of success

© Detlef Göckeritz

Automotive giant GKN Driveline started welding drive compo­nents with lasers 14 years ago. Now the tried-and-tested system is moving to the next round — featuring disk lasers — on three continents.

A production hall in the Black Forest. Antonio Torres, welding specialist at the GKN Driveline plant in Mexico, and his colleagues Martín Sánchez and Neil Plant are watching closely to see how the machine handles the drive components they brought with them. A gripper picks up what’s called a tulip cover for a flange. Shaped like an inverted top hat, the cover is slightly bigger than a fist. Flange and housing have already been joined in a press fit.

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Drive components subjected to severe strains: countertrack joint (left) and tulip cover for flanges (right) (Photo: Detlef Göckeritz)

They are placed in a parts holder on a carousel and are clamped from the inside. The carousel rotates to the next position, where an inductor is placed around the head of the component. The metal smokes and glows while the infrared beam of a pyrometer measures the temperature. Within seconds, the upper end of the flange is heated until it becomes incandescent. The carousel rotates into the welding cell. The light from the disk laser welds six neat seams before the part cools too far — again monitored by a pyrometer. At the final station, the gripper removes the part from the mold and inserts it in the marking laser box, where it is inscribed. The tulip cover is lowered onto the conveyor belt. The whole process takes just a few seconds.

Retooling times, range of variants — we get better with every new system.”
Antonio Torres

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Antonio Torres, welding specialist at the GKN Driveline plant in Mexico, and his colleagues Neil Plant and Martín Sánchez. (Photo: Detlef Göckeritz)

Torres has connected his laptop to keep track of every single parameter. “I’d heard a lot about this kind of system from my colleagues, but I still find the cycle times and accuracy demonstrated here to be pretty impressive.” He arrived in southern Germany from Celaya in central Mexico a couple of days ago. The purpose of his visit to KMS Automation, a manufacturing technology company, was to take a look at the machine that will soon be improving his production output.

Deep welding with disk lasers

GKN Driveline is one of the largest suppliers of automotive driveline systems, offering a wide range of drivetrain solutions. Here precisely timed mass production flow joins high quality expectations. GKN’s plant in Mexico is currently being expanded and Torres is starting to manufacture a broader range of product versions. “This also means that we will be using new production technologies. From now on, solid-state lasers will play a permanent role in our manufacturing operations.”

GKN Driveline

GKN Driveline is the world’s leading supplier of automotive driveline components and systems. As a global company serving the world’s leading vehicle manufacturers, GKN Driveline develops, builds and supplies an extensive range of automotive driveline components – for use in the smallest car to premium vehicles.

Neil Plant didn’t have to travel quite as far as Torres to get to the Black Forest. He works at the main GKN plant in Birmingham, UK, as Manufacturing Development Manager Welding. As Plant points out, “Laser welding itself is nothing new for GKN. We adopted this type of CO₂ laser system for welding as the standard for many of our products 14 years ago, because it’s stable, fast, and needs no touch-up work. Laser welding processes always seem expensive at first, but they have significantly reduced our production costs each and every time.”

Most companies that produce welded drive components opt for CO₂ lasers. Until now, only they were capable of achieving the necessary depth for weld seams that have to hold up under constant high stress. Now solid-state lasers can do the same thing, thanks to the TRUMPF engineers who have greatly improved the beam quality of disk lasers in recent years. A tangible result of their efforts is Torres’s new machine.

“Our customers expect us to have full mastery of laser welding technology.”
Huo Chenhui

Production engineer Huo Chenghui at the GKN Driveline plant in Shanghai, China. (Photo: Propaganda Studio)

Production engineer Huo Chenghui at the GKN Driveline plant in Shanghai, China. (Photo: Propaganda Studio)

Neil Plant says, “The new laser welding systems have become standard in our operations, and are gradually being rolled out in more and more of our international plants.” One of these will soon be in the plant at Shanghai, China, where production engineer Huo Chenghui works. “Our customers expect us to be up to date on this technology. We were so impressed with the efficiency of disk lasers that we intend to use them for all our smaller components in the future.”

Huo Chenghui plans to soon order the same disk laser welding system that Torres has. “Our German colleagues in Zwickau have already adopted this approach with very positive results. We want to follow their example.”

Inductor as a perfect partner

In fact, it was in Zwickau that GKN started working with laser welding. Zoran Bubic, who is in charge of central processes and operational planning there, recalls: “We collaborated with TRUMPF 14 years ago on a welding process using CO₂ lasers. One of the challenges at that time was to find a clever way of preheating the workpiece.”

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Zoran Bubic is in charge of central processes and operational planning at the GKN plant in Zwickau, Germany. (Photo: Mirko Hertel)

Their solution was induction heating. “It’s ideal for welding as it provides rapid, localized heating and can be easily integrated into the process, which since then has produced stable, satisfactory results,” says Bubic. “And then, a couple of years ago, in response to growing customer demand, we wanted to add a second welding system. It was to greatly lower the production costs but, of course, achieve the same quality level.”

Together with TRUMPF, the engineers at GKN Driveline Germany decided to employ a TruDisk 5302 fiber-guided disk laser in the welding process. The laser applications laboratory in Ditzingen worked with GKN Driveline to define the welding parameters, including heating temperature, laser output, focal position, welding rate and others. As Bubic explains, “Our customers are among the world’s top carmakers and they have a very exact idea of how their components are to be. For instance, their specifications for welded seams cover pages and pages, defining tolerances for porosity, joining errors, undercutting, pore clusters and weld convexity. With the help of the TRUMPF laboratory, we were able to meet all the product’s specifications with a disk laser solution.”

“The new disk laser welding system has signicantly cut our production costs.”Zoran Bubic

The system was integrated by KMS Automation, based in the Black Forest village of Schramberg. The company developed a concept that would allow the various elements to be combined into one production machine with short cycle times. TRUMPF Hüttinger is responsible for supplying the generator, process energy and inductor for preheating, while TRUMPF supplies the laser source, optical cables, optics, and the TruLaser welding cell.

Goodbye helium

“We have been using this solid-state laser welding system for two years, and it has let us, once again, reduce our production costs considerably,” reports Bubic. “In addition to its smaller footprint — our old CO₂ system needed 100 square meters, its successor only 35 — it also uses less energy. The new system has an efficiency rate of nearly 30 percent, which is much more than that of the previous system.”

 

TruDisk disk lasers

TruDisk lasers are ideal for welding, cutting or surface treatment: TruDisk lasers prove themselves in all places where metals are processed to produce high-quality products and where continuous high power and very good beam quality are required – this includes industries such as the automotive industry and automotive supply.

TrueHeat MF Series3010 – 7030

TruHeat MF generators from TRUMPF Hüttinger are powerful induction generators. They can be used both in traditional and high-tech applications.

Another advantage of the solid-state laser is that it operates at a wavelength that the material can absorb more efficiently. Thus it requires far less laser power. “But the biggest factor is the shielding gas,” explains Bubic. “Helium is expensive right now. The CO₂ system blows some 16 liters of this gas onto the workpiece every minute in order to suppress metal vapor plasma. Since solid-state lasers don’t create plasma, we don’t need shielding gas at all.”

In the Black Forest, Torres pulls on white safety gloves and picks up the hot, freshly welded tulip cover. “We get better with every new system. This one enables us to weld a wider range of component versions using a single machine while reducing retooling times.” He looks at the component and adds: “Most of the advances made in joining in the future will come from laser welding.”

Contact at TRUMPF:

Hakan Kendirci
Industry Manager Automotive Powertrain
Phone: +49 (0)7156 303 – 36890
hakan.kendirci@de.trumpf.com

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