Carbon's coming day
abrn.com
Jan 17, 2005
By: Tim Sramcik
Automotive Body Repair News
Automakers begin gearing up production of lightweight material
Efforts to build more fuel-efficient vehicles have taken auto engineers around the world and into labs, universities and factories searching for new technology. Closer to home, lightweight carbon fiber composite material used by the military is slowly proving to be one of the most promising answers yet.
U.S.-built fighter jets and helicopters currently buzzing over the Iraqi desert owe much of their performance capability to lightweight structures made from carbon fiber reinforced plastic (CFP). Consisting of woven carbon fibers and resin, CFP offers the strength and stiffness of steel with a 50 percent reduction in weight (and a 30 percent reduction compared to aluminum). The reduced weight allows military craft to add on heavy navigation, communication and munitions systems and still operate without increased strain on fuel supplies.
Scientists believe CFP can provide similar benefits to automakers. Current studies predict a potential 68 percent weight reduction and 40 percent increase in fuel efficiency in vehicles equipped with CFP parts in place of steel and aluminum.
Automakers have taken note. In the last two years they’ve stepped up their interest in CFP, although much of their focus has been on building lightweight parts for performance vehicles. Still, these efforts are bearing results that eventually could make CFP an integral part of all vehicles.
For several decades, aftermarket companies have built CFP parts—typically ultra-light, ultra-expensive hoods and panels—for performance enthusiasts looking to erase every extra pound from their vehicles. Mercedes-Benz entered the fray two years ago with its 2003 SLR Mclaren, the first series car to be fitted with a carbon fiber front structure. At the same time, BMW was equipping its 2003 M3 CLS (not available in North America) with a production line CFP roof.
“We decided to go with carbon fiber parts because this was a performance automobile and we needed to reduce weight as much as possible,” says BMW Spokesman Dave Buchko.
American and Asian designers quickly followed suit. Chevrolet added a CFP hood to the 2004 Z06 commemorative edition Corvette. Acura included both a CFP hood and spoiler on its 2004 NSX-R. The fact that the SLR, CLS, Corvette and the NSX-R all are expensive limited-edition vehicles and, therefore, prime candidates for current CFP technology, points to the challenges automakers face when using CFP parts.
As with any new manufacturing technology, costs can be prohibitive. Raw materials for CFP cost $30-$35/kg ($14.5-$15.75/lb.) compared to $5-$7/kg. ($2.25-$3.15/lb.) for aluminum.
CFP parts also are difficult to construct and usually require time-consuming, multi-step processes. For example, NSX-R parts must first be cured in a high-pressure oven. They then require a 10-hour lamination process, are wrapped in baking film and vacuumed to consolidate the laminate. The lay-up cures for two to three hours in an autoclave (typically used for aircraft manufacturing) at two to three atmospheres of pressure. Cooling requires an additional five hours.
One further drawback is material waste. CFP manufacturers usually deliver their product in standard size matted rolls. Chunks of these rolls, sometimes as much as one third, must be trimmed to fit parts.
Technological advances, driven by automakers’ interest in CFP, are answering all these challenges.
Market forces already have dropped the price of raw materials from the $200-$300/kg. ($90-$135/lb.) range of the late 1990s. Industry experts believe that as the market grows, costs should drop to a competitive $10/kg. In 2002, scientists at the Oak Ridge National Laboratory started work with Hexcel Carbon Fibers to develop low-cost carbon fiber (LCCF) technologies to reduce costs an additional $1.50/lb. ($.68/kg.).
Automation is gradually proving a remedy for time constraints. In order to build the SLR, Mercedes became the first auto manufacturer to invent an automated process for creating CFP. Previously, CFP was positioned in layers by hand. BMW started the world’s first highly automated CFP part production process at its Landshut, Germany, plant to build the 1,000 to 1,300 roofs needed each year for the CSL.
Significant help is coming from other businesses. Fiberforge, a small startup company in Basalt, Colo., has developed CFP technology that addresses both lay-up and forming problems. Fiberforge has automated the lay-up process with technology that positions 55 mm. wide strips of individual carbon fibers and injects them with a resin to create “tailored blanks.” The process also automatically places exact numbers of fibers at precise angles and produces a high fiber-to-resin ratio, both of which help maximize part strength.
According to David Dwight, vice president of marketing for Fiberforge, the new lay-up process replaces costly, time-consuming handwork and eliminates the need for wasteful CFP rolls. Because Fiberforge’s process can use less expensive materials such as glass fibers in non-critical part areas, it lowers costs as well, he claims.
Once a tailored blank is produced, a thermoforming process shapes the blank into a part. Dwight explains Fiberforge uses thermoforming due to its similarity to traditional steel stamping used for automotive parts and because it can be used in high-speed processing needed for lower cycle times. Fiberforge’s current thermoforming cycle time is four minutes, but Dwight is confident it can be improved to one.
He, however, cautions against high expectations for CFP manufacturing. “There are still issues to be worked out, such as cosmetic concerns, for example how the material looks and how it can be painted,” he says. “Early on there’s a good chance most of these parts will be structural. They’ll be used for the inside panels of doors, not the outside.” Dwight also says CFP may prove not to be the best material for every part. “There probably will be some places where steel or aluminum might be a better alternative,” he says.
Gazing into a CFP future
Gauging where CFP technology is immediately headed can be difficult because manufacturers consider this information proprietary and remain tightlipped about their plans. Buchko was unable to comment on how BMW will continue to use its technology. Dwight similarly could not comment on what automakers Fiberforge might be working with or what parts they could be manufacturing. Still, there’s sufficient reason to believe CFP parts will play a significant role in the near future of automotive development.
Foremost, demands for cleaner air and better fuel efficiency will continue to drive vehicle design. Lightweight CFP parts offer available, ever more accessible solutions to both challenges. Automakers may move toward other solutions, such as hybrid vehicles and alternative fuels, but hybrids still form just a small percentage of automotive fleets and an alternative fuel economy currently is far more science fiction than fact. Moreover, as hybrids and alternative fuel vehicles become more popular, CFP parts could benefit them because their lightweight designs will optimize fuel economy and performance.
Also pushing the development of CFP parts will be the dark clouds beginning to form around the petroleum market. Energy experts such as petroleum geologist Colin Campbell predict oil production will peak by 2010. Before supplies are completely exhausted (possibly by 2050), exploding industrial growth in China and other developing nations will put a growing strain on the petroleum market. Fuel demands and prices could, and most likely will, skyrocket.
To keep their products marketable, automakers will have to produce vehicles that can be operated affordably. Lightening the load is a necessary step. It’s also a step automakers can take care of on their own, without assistance from the energy industry.
For their part, consumers can be counted on to accept and even demand lightweight designs, especially if it means keeping transportation affordable. Even in the United States where bigger is better and the SUV/light truck market remains hot, motorists shouldn’t mind stepping into lighter vehicles. In fact, a comparable trend already exists.
In America’s consumption-crazed culture, losing weight has been a national obsession (and probably a necessary one at that). It would only be appropriate in a culture equally car crazy that vehicles too would shed some pounds to preserve their existence
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