Tech Tips September 2012

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Carbon-Fiber to Hit First Mid-Volume Production Car Next Year

An automotive industry trade publication, Automotive Engineering International, reported Tuesday that a mid-volume production car will contain significant amounts of carbon fiber beginning as early as next year. Until now, carbon-fiber has only been used on low-volume specialty vehicles such as the Corvette ZR1, which features carbon-fiber fenders, roof, hood, rocker panels and other parts. However, less than 1,500 ZR1s are sold each year.

Thanks to a new processing technology for carbon-fiber body panels developed by Plasan Carbon Composites, the material will debut for the first time on a production vehicle with a yearly volume of as much as 50,000 units, according to the AEI report. The mid-volume car will reportedly feature a carbon-fiber hood, roof, and fenders and the panels on the future vehicle will be a combination of exposed weave (photo top) and painted finish (photo bottom).

While this is still not a high-volume production vehicle, (such as the Ford Fusion and Ford Escape, both of which sell approximately 250,000 copies a year) a shop will be 50 times more likely to see one of these than a Corvette ZR1.

“It will be the first time that carbon fiber has been used this extensively on a base production car anywhere in the world,” Gary Lownsdale, Chief Technology Officer of Plasan Carbon Composites, told AEI.

While a secrecy agreement prevents Plasan from naming the vehicle or the automaker, details will emerge soon enough, as body panel production is scheduled to begin at Plasan in January 2013.

Last August, Plasan was awarded almost $2.5 million from the Department of Energy for a project to evaluate and validate models for predicting the crash behavior of carbon fiber composites.


GM Welding Breakthrough Enables More Use of Aluminum

General Motors Research & Development has invented an industry-first aluminum welding technology expected to enable more use of the metal on future vehicles.

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, but, beginning in 2013, GM plans to use this technology more extensively.

“This new technology solves the long-standing problem of spot welding aluminum, which is how all manufacturers have welded steel parts together for decades,” said Jon Lauckner, GM chief technology officer and vice president of Global R&D. “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.”

GM says the 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.


Honda Develops New Welding Technology, UHSS Structure for New Accord

One of the first cars with ultra high strength steel body structure landed in showrooms on Wednesday.

Honda has developed some new technology for vehicle construction, and they have applied it for the first time in the world to a mass-production vehicle; and not just any mass-production vehicle, the Honda Accord, one of the top-five selling vehicles in the United States.

The newly redesigned 2013 Honda Accord went on sale in the United States on September 19, and its construction is the result of Honda’s next-generation Advanced Compatibility Engineering (ACE) body structure which utilizes the new welding technique as well as hot-stamped and other ultra-high strength steels to build its cabin structure.
The Accord’s subframe is made with a combination of steel and aluminum joined together with a process called Friction Stir Welding (FSW). The continuous weld technology generates a stable metallic bond between steel and aluminum by moving a rotating tool on the top of the aluminum which is lapped over the steel with high pressure. Honda says the resulting weld strength is equal to or greater than conventional MIG welding.

Honda also developed a non-destructive inspection system for quality control that uses a highly-sensitive infrared camera and laser beam to inspect every unit. The carmaker says the Friction Stir Welding system it developed for this process can be also be used for aluminum-to-aluminum welding and could be used for production of a full-aluminum subframe.

High Strength Steel Structure

The subframe however, should not cause many repairability issues according to I-CAR Technical Director Jason Bartanen, as Honda provides no repair procedures at all for the part, and specifies complete replacement only.

“What will cause some issues is the high strength steel used in this car’s body structure,” said Bartanen speaking from the I-CAR Tech Centre in Appleton, Wisconsin.

The newly redesigned 2013 Accord body uses 55.8-percent high-tensile steel, more than in any previous Accord. And 17.2-percent of the steel is grade 780, 980 and 1,500 MPa, extremely high grades that have never before been used in any Accord, and in fact, very few other cars, according to Bartanen.

“This is one of the first cars to use such high strength steel (1500 MPa) in its body structure,” says Bartanen. “Most applications only use it only for bumper beams. But the new Accord uses ultra-high strength steel in its A pillar and B pillar reinforcements as well as its rocker reinforcements. Honda is requiring MIG brazing only in these areas.
While Honda is not the very first to build such a body structure, none of the previous vehicles even come close to the sales volume of the Accord. “The Volvo XC60 is also using similar ultra-high strength steel (1,500 MPa) in the structure,” Bartanen noted.

The Accord has historically sold between 250,000 and 400,000 units a year compared to XC60 sales of approximately 25,000.

Bartanen said I-CAR is currently updating its Honda and Acura training available online. The new Accord will be covered in I-CAR’s Collision Repair Overview for Honda and Acura Vehicles (HON01) and should be available within the next few months.

“We have an Accord body in white on its way here right now,” Bartanen noted. “We are going to paint it to show the various steels used in this car and prepare it for display at the SEMA show.”

The ninth generation Accord, which also contains Forward Collision Warning and Lane Departure Warning technologies, officially debuted at dealerships across the U.S. on September 19 at a base price of $21,680 plus destination charge.

New VW Golf Sheds Weight with Ultra High Strength Steel

Volkswagen unveiled the new Golf at a press conference in Berlin, Germany this week. The seventh-generation version of the best-selling car is 220 pounds lighter than the outgoing car, thanks in part to the use of nearly five times more ultra-high-strength steel in the body shell.

The new version’s body-in-white is 51 pounds lighter than its predecessor. The share of high-strength steels overall has gone from 66 percent in the previous Golf to 80 percent in the new one. Of this, the share of ultra-high-strength steel has gone from six to 28 percent. Key body components are joined with seamless laser welds instead of spot welds.

Even though the new version is lighter, it is 2.2 inches longer than the old car, and the wheelbase has grown by 2.3 inches.

The car also offers six airbags (dual front, side, and side curtain airbags), front safety belt pre-tensioners with load limiters and emergency locking retractors. The Golf also comes with Volkswagen’s Intelligent Crash Response System. In certain types of collision, the fuel pump is shut off instantaneously, the doors are unlocked, and the hazard lights switched on.