Should help improve fuel economy too!
Wayne Gerdes -
CleanMPG - Sept. 26, 2012
GM R&D invented an industry-first aluminum welding technology expected to enable more use of the lightweight metal on future vehicles.
According to the GM PR, its new resistance spot welding process uses a patented multi-ring domed electrode that does what smooth electrodes are unreliable or unable to do – welding aluminum to aluminum. By using the new heads and process, GM expects to eliminate nearly two pounds of rivets from aluminum body parts such as hoods, liftgates and doors.
GM already uses this patented process on the hood of the Cadillac CTS-V and the liftgate of the hybrid versions of Chevrolet Tahoe and GMC Yukon. GM plans to use this technology more extensively starting in 2013.
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 until now, not robust for use on aluminum in today’s manufacturing environment. GM’s new welding technique works on sheet, extruded and cast aluminum because GM’s proprietary multi-ring domed electrode head 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.
Aluminum use in vehicles offers many advantages over steel. One pound of aluminum can replace two pounds of steel. It is corrosion-resistant and offers an excellent blend of strength and low mass that can help improve fuel economy and performance.
In addition and according to AluminumTransportation.org, a 5 to 7 percent fuel savings can be realized for every 10 percent weight reduction, and substituting lightweight aluminum for a heavier material is one way to do it. Cars made lighter with aluminum also can accelerate faster and brake quicker than their heavier counterparts.
I cannot think of a single GM vehicle that is not in need of a desperate diet and maybe this new process is one way for them to get there? The new Cadillac ATS is probably GM’s best example of doing all the little things to make a vehicle right. With a base curb weight of 3,315 pounds, the ATS is the lightest luxury sport sedan in the world contributing to better fuel economy, quicker acceleration and nimble handling. Along with Ultra high strength steels throughout the car it sports an aluminum hood plus magnesium engine mounts, a laminated windshield that is lighter than traditional tempered glass and door trim panels made from natural fibers are lighter than the standard-issue plastics.
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