Volkswagen’s R&D chief Dr. Ulrich Hackenberg is cautiously optimistic about the use of carbon fiber technologies in volume cars. Said Hackenberg today in Wolfsburg:
“Carbon fiber technology is still too expensive for volume cars. For some parts of the car it will make sense in the near future.Looking at the CPO2 and emission limits there are some areas in the car that will make sense. But not in the whole car.”
One area of the car that is likely to see carbon fiber components is the roof of the car. A CFRP roof can not just shave lbs off the car, it can also improve its ride. Explained Hackenberg:
“If I change a roof from steel to carbon fiber, I can save some 10 kg. If you have a low weight in the roof area, you lower the center of gravity, that’s good for the car.”
Hackenberg said Volkswagen is testing the use of aluminum sheets and carbon fiber sheets for the next generation of the Passat, “and we have found ways to use these materials in a normal transfer facility to build a normal car.” The challenge here are new joining techniques that mate non-weldable CFRP with other materials such as aluminum or steel. The other challenge is to make CFRP parts fast enough to keep up with a mass-produced vehicle.
As we have seen in the report from the inside of the LFA production, pre-preg CFRP can take hours to assemble, and even more hours to cure in the autoclave.
Hackenberg explained a technology, first used in the Porsche 918, where “the lower parts of the safety cabin, up to the bottom of the A pillars, are done in one shot. We have a tool that closes, the CFRP material is brought into this form, the form is closed, then you inject the resin. Takes half an hour.”
This is still too slow for mass production, but Hackenberg hopes to bring down cycle times to a few minutes, which would be similar to what a roof from hot formed steel would take.
All Herr Hackenberg has to do is prescribe multiple vendor sites to pre-form CFRP roofs, so that they can be phased into the assembly line outside of the critical time-flow of production.
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I think the issue is capital and labor costs. If a giant steel stamping machine can stamp out a roof in 2 min then you only need one (or maybe two) to support Chattanooga’s 30/per hour production rate. If a carbon fiber roof takes 30 min then you need at least 15 autoclaves and the people to staff them to support the same production rate.
jmo – –
Yes, I am sure you’re right if done on the production line in Chattanooga. My point, though, was that if the pre-production of roofs is done by automatic facilities off-line at the CFRP vendor locations, then those multiple autoclave baking times won’t be part of the assembly times at the car plant. But you may still have a point about increased labor/material costs, regardless of where the roofs are made.
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I am glad they get it about roofs. It’s too bad that they make you get giant sunroofs that don’t even open on the A5/S5/RS5 here in the states though..WTF. Glass is heavier then steel or carbon fiber.