In 2005, General Motors started production of the GMT 900 platform used in its GMC Yukon and Sierra, and Chevrolet Tahoe, Suburban and Silverado vehicles. At the time, industry analysts called the GMT 900 full-size sport utility vehicles (SUVs) and pickup trucks a “make or break” product line for General Motors. Van Rob was asked to manufacture the GMT 900 “rad support”— a critical front end component that supports the radiator and connects to the fenders, hood latch, headlights and grille. Because General Motors sold about 1.8 million of the preceding GMT 800 vehicles annually, volume expectations for the next generation GMT 900 were high. Van Rob would produce approximately 900,000 rad supports for new pickup trucks and a similar amount for the SUVs. “With that kind of volume you have to be sensitive to manufacturing costs,” says Bo Lindgren, vice president of engineering at Van Rob’s Corporate Centre in Aurora, Ontario Canada. “The challenge was to achieve the best manufacturing environment with high quality and low fallout. We’d have to weld at a high speed to get that output.”

The aluminum rad supports, used in the GMT 800s and initially the GMT 900 SUVs, posed some manufacturing challenges. “We asked ourselves how we could build the part smarter, making it better and cheaper,” says Lindgren, whose goal was to have a new part ready for the pickup truck production which began a year later. “We looked for ways to redevelop the part in steel to lower the cost, while maintaining the weight.”

Traditional MIG welding was too slow and distorted the profile. The production speed and quality Van Rob wanted required a new welding method. Van Rob conducted a number of tests and studies, reviewed various welding options, and decided upon CO2 laser technology, primarily for its high output rates and low distortion, but also for its safety and beam switching capabilities. “With a cycle time of twelve seconds, you have to weld fast and produce a nearly perfect part,” explains Lindgren. “There’s no time for repair work. Either it works or it doesn’t. If it doesn’t work, you shut down the car plant and no one wants to be the one to do that.” Because laser welding is much faster than MIG welding, fewer manufacturing cells are needed to accomplish the work in the same amount of time. “When you can laser weld five times faster in one cell, you need fewer cells,” Lindgren explains. “The number of MIG weld cells required would have taken up too much room. Also, five times more equipment would have put more heat into the parts and distorted the profiles.” The speed of laser welding also meant fewer weld fixtures and reduced tooling costs. “If you weld faster, you can remove one or two fixtures,” says Lindgren. Eliminating fixtures was good news, especially for the automotive company, for which tooling is classically an upfront cost.

Lindgren’s team began running part trials, testing different joint configurations, and investigating logistics such as part clamping and challenges posed by material coating. “All of this homework is important, especially with laser welding,” he says. “You have to understand the part design and make it as good as possible for the production method. It was during this process that we got heavily involved with TRUMPF.” Lindgren and his team went to Europe to learn more and discover how others were using the technology. Through TRUMPF, Lindgren was able to witness Volkswagen using lasers in manufacturing. Using their new knowledge and existing manufacturing expertise, Lindgren’s team developed prototypes for validation testing involving a fully built-up car. “80 percent through the lifecycle tests, even the skeptics agreed the process would really work, and work well,” says Lindgren.

Six pieces in the rad support assembly are laser welded. Lindgren estimates that they laser weld about 14 miles a day for this assembly. His team selected a mix of weld joints to best fit each profile. A butt weld was used on four of the parts for efficient material usage. In profiles longer than 1.6 meters, they chose an overlap weld that would work well even in material with a heavy side bend (camber) in the coil.

Another creative weld solution was required when a last-minute change introduced galvanized material. “Welding zinc-coated (galvanized) steel creates a lot of gas and the welds can get porous,” explains Lindgren. “So we used a t-joint, which gave us two sides where the gas could disappear very fast and that worked out quite well.” Variable thickness material proved to be another challenge ably handled by the laser. With weld parameters set up to change on-the-fly, the laser welded well in both thick and thin material. Going from 1 mm to 1.9 mm material in the same blank was not a problem.

Using steel in place of aluminum resulted in an automatic cost savings. The laser technology also saved valuable time, floor space, and equipment and fixturing expenses. Van Rob’s design yielded another benefit: quality improvement. “The new part performed better than the original,” says Lindgren. “At the end of the durability cycle, the aluminum part had some cracks, which were acceptable, but amazingly, in the steel parts there was no fatigue at all. The steel design was stronger.” No wonder Van Rob has been a GM Supplier of the Year for the last 10 years. The secret to its success ? “We’re constantly working on the product to make it better and manufacture it smarter,” explains Lindgren. “That’s why we buy the latest technology from TRUMPF. You have to be a leader, or someone else sets the benchmark and you just try to catch up.”