GM’s resistance spot welding process improves fuel economy and driving performance thanks to weight reductions.
DETROIT—General Motors expects to use more aluminum now that its R&D team has perfected a new welding technology the company says will enable use of the lightweight metal on future vehicles to improve fuel economy and driving performance.
The resistance spot welding process uses a patented multi-ring domed electrode that does what smooth electrodes are unreliable at doing—welding aluminum to aluminum. GM expects to eliminate nearly two pounds of rivets from aluminum body parts such as hoods, liftgates and doors using the technology.
GM already uses the process on the hood of the Cadillac CTS-V and the liftgate of the hybrid versions of Chevrolet Tahoe and GMC Yukon.
Spot welding uses two opposing electrode pincers to compress and fuse pieces of metal together, using an electrical current to create intense heat to form a weld. The process is inexpensive, fast and reliable, but was not robust for use on aluminum in today’s manufacturing environment. GM’s new welding technique works on sheet, extruded and cast aluminum thanks to a multi-ring domed electrode head that disrupts the oxide on aluminum’s surface to enable a stronger weld.
Historically, automakers have used self-piercing rivets to join aluminum body parts, because of variability in production with conventional resistance spot welding. However, rivets add cost and riveting guns have a limited range of joint configurations. In addition, end-of-life recycling of aluminum parts containing rivets is more complex.
“No other automaker is spot-welding aluminum body structures to the extent we are planning to, and this technology will allow us to do so at low cost,” said Blair Carlson, GM manufacturing systems research lab group manager. “We also intend to consider licensing the technology for non-GM production in automotive, heavy truck, rail and aerospace applications.”
According to Ducker Worldwide, a Michigan-based market research firm, aluminum use in vehicles is expected to double by 2025. The material offers many advantages over steel. One kilogram of aluminum can replace two kilograms of steel. It is corrosion-resistant and offers a blend of strength and low mass that improves fuel economy and performance.
A 5% to 7 % fuel savings can be realized for every 10% weight reduction, according to AluminumTransportation.org.
Check out the video below to see the process in action.