For Immediate Release: Monday, Sept. 24, 2012
GM Welding Breakthrough Enables More Use of Aluminum
Increased use of lightweight metal can help improve fuel economy, performance
DETROIT – General Motors Research & Development has invented an industry-first aluminum
welding technology expected to enable more use of the lightweight metal on future vehicles,
which can help improve fuel economy and driving performance.
GM’s new resistance spot welding process uses a patented multi-ring domed electrode that
does what smooth electrodes are unreliable at doing – welding aluminum to aluminum. By using
this 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.
“The ability to weld aluminum body structures and closures in such a robust fashion will give GM
a unique manufacturing advantage,” said Jon Lauckner, GM chief technology officer and vice
president of Global R&D.
“This new technology solves the long-standing problem of spot welding aluminum, which is how
all manufacturers have welded steel parts together for decades,” Lauckner said. “It is an
important step forward that will grow in importance as we increase the use of aluminum in our
cars, trucks and crossovers over the next several years.”
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.
“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 an
excellent blend of strength and low mass that can help improve fuel economy and performance.
According to AluminumTransportation.org, a 5 percent 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.
“GM aims to be an industry leader in mass efficiency,” said Roger Clark, manager of the GM
Energy Center. “Many little things can add up to big improvements in fuel economy. Incremental
mass reductions, like using welds instead of rivets, can help our customers save at the pump.”
General Motors Co. (NYSE:GM, TSX: GMM) and its partners produce vehicles in 30 countries, and the
company has leadership positions in the world's largest and fastest-growing automotive markets. GM’s
brands include Chevrolet and Cadillac, as well as Baojun, Buick, GMC, Holden, Isuzu, Jiefang, Opel,
Vauxhall and Wuling. More information on the company and its subsidiaries, including OnStar, a global
leader in vehicle safety, security and information services, can be found at http://www.gm.com.
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