What are the promises and pitfalls of carbon fiber?
by Jeremy Korzeniewski on Sep 3rd 2009 at 7:47PM 
For the last century or so, cars and trucks have predominantly been formed from one material in particular: steel. It's not hard to see why – steel is relatively inexpensive, highly abundant and easy to form into somewhat complex shapes that can be repaired with mostly basic tools.Recently, though, we've seen an uptick in the amounts of alternative materials used in the automotive industry. The most popular material next to steel would be aluminum, which is lightweight and can be made plenty strong enough for use in our vehicles. On the other hand, it takes a lot more energy to produce and is not as easy to work with as steel. What other alternatives are there?
Carbon fiber. You've surely heard of this wonder material, which has certainly made a recognizable appearance on the automotive scene over the last few years. Carbon fiber is light, strong and can be molded into all kinds of interesting shapes. Plus, it looks really cool... but it's not all lollipops and rainbows. Click past the jump to read more about carbon fiber's many promises, and its pitfalls.
Gallery: Carbon Fiber Lotus Elise
So, um, what's carbon fiber?
We'll let the all-knowing Wiki explain:
Carbon fiber (alternatively called carbon fibre, graphite fiber, or carbon graphite) is a material consisting of extremely thin fibers about 0.005–0.010 mm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber... Several thousand carbon fibers are twisted together to form a yarn, which may be used by itself or woven into a fabric.
Fine. How 'bout in English? Think of a piece of cloth from the fabric store. The same way that cloth is woven together, thin strands of nearly pure carbon are twisted into yarns and then into fabrics. Obviously, you can't make a car from fabric (unless you're BMW, of course), so what do you do with it?
Sheets of carbon fiber fabric are layered into a specific shape, generally by hand using a complex mold, and a polymer is applied that binds the carbon fiber fabric together. More often that not, that polymer is an epoxy that hardens through heating, pressure or both. After the piece is fully cured, it's removed from the mold and is ready for use. Clear as mud? Perfect, let's move on.
Gallery: KTM X-BOW roadster
What's so great about carbon fiber anyway?
As we touched on in the opening paragraphs, parts fashioned with carbon fiber are inherently light and strong. That's perfect for cars and trucks (as well as airplanes, boats, bicycles...) as it allows a structure that's safe, has good driving dynamics and is significantly lighter than the same piece from either steel or aluminum. As you likely know, a lightweight automobile can make use of a less powerful engine and therefore tends to get much better fuel mileage.Great! Why don't we make all of our cars from carbon fiber?
Well, it's not quite that simple. Carbon fiber is strong and light, but it's also expensive and takes much longer to fashion into usable parts than most other competing materials.
Further, while steel and sometimes aluminum can be reshaped and repaired after an accident, that's not really true of carbon fiber, which may fail spectacularly when finally pushed beyond its limits. When damaged, carbon fiber can splinter into a number of sharp, dangerous bits that can't easily be reassembled to make a whole unit.
Finally, when it comes time to replace the automobile, there are a number of relatively simple steps that can be taken to recycle plastic, steel and aluminum. Carbon fiber, though, isn't so easily recycled and reused into new automotive parts.
So, where do we go from here?
That's the $64,000 question. It certainly seems likely that carbon fiber will continue to be used to make high performance and race cars for the foreseeable future due to its laudable strength-to-weight characteristics. That said, we're probably still quite a number of years away from seeing mass-produced cars sold on dealer lots made predominantly from this wonder material. In the meantime, we continue to look forward to new advancements in technology to lower the cost and time associated with creating high-quality pieces from carbon fiber along with any new materials that can help reduce the prodigious weight of modern automobiles.
If you have your a topic you'd like us to cover in a future Greenlings column, leave a comment on this post or send us a note.
Reader Comments (Page 1 of 2)
wincros 8:24PM (9/03/2009)
The article ignores the many health warnings for carbon fiber. Almost any inert, small fiber floats in the air and lodges in the lungs causing everything from emphysema to lung cancer. It is thought that carbon fiber is very similar to asbestos in its effects on lungs. There are hazards from the non-inert coatings added to the fibers to improve their handling in an industrial environment. The chemicals and resins used to bond the fibers have their problems as well.
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skierpage 11:58PM (9/03/2009)
There *AREN'T* many health warnings for carbon fiber (reinforced plastic, to give its full title). Here's the OSHA manual section, http://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_1.html#6 It doesn't sound any more dangerous than fiberglass, where are the thousands of dead Corvette drivers? The epoxy resins are a skin irritant until they cure, and then the matrix sounds nice and safe and inert to me. "PAN-based carbon fibers [the majority] did not cause tumors when the same test was conducted... Carbon fibers commonly in use are also greater than six micrometers in diameter, making them unlikely to be respirable" Many asbestos forms are much thinner so they can get in the lungs and cause asbestosis, and asbestos is a known carcinogen
Cite your sources.
matte 8:12AM (9/04/2009)
You might have mixed up Carbon Fibers with Carbon Nano-Tubes.
The latter have given rise to concern similar to Asbestos-induced lung cancer
miles 8:25PM (9/03/2009)
Fabulous stuff, but utterly un-mass-producable, so far as I've heard.
Is anyone working on the volume production issue?
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skierpage 12:17AM (9/04/2009)
It's definitely not mass production currently. Tesla claims their Roadster at $109,000 is the cheapest car you can buy with all body panels made from carbon fiber. The Mercedes McLaren SLR ($495,000) is the next cheapest car, though the discontinued Porsche Carrera GT (444,400) had a carbon fiber monocoque.
Each Boeing 787 Dreamliner uses 35 tons of CFRP, made with 23 tons of the fiber, which is either going to starve other uses of the material, or reduce the cost, or neither.
Watch videos of Pagani Zondas being made like http://www.youtube.com/watch?v=tMeuUdIcw7E , it's more craftsmanship than making a suit.
Chris M 2:48AM (9/04/2009)
There is a spinoff from the Rocky Mountain Institute, called "FiberForge" that is attempting to develop new ways of manufacturing and shaping carbon fiber, and to bring the cost down enough to make it practical for use in average price autos.
They've still got a lot of work to do.
Dan Mosqueda 7:21AM (9/04/2009)
I know that several bicycle manufacturers use it. Trek makes several Madone bikes out of carbon fiber. The technology (Net Molding) is restricted to manufacturing in the United States apparently. http://www.trekbikes.com/za/en/bikes/road/madone/6_series/technology/
It seems an idea would be to start using carbon fiber for individual pieces in a car such as seats or larger interior parts, plus the standard good, trunk, etc... as a way to cut weight.
GoodCheer 9:54AM (9/04/2009)
There are a lot of efforts at developing mass production techniques that center around thermoplastics (plastics that can be melted) rather than thermo-set plastics (plastics that cure to a solid, and will combust rather than melting).
Most of these approaches involve first fabricating flat panels, then melting and stamping those panels into finished form. The flat sheets (blanks) generally need massive and expensive forming tools to insure low porosity and high fiber fraction. The limitations in the shape of finished products made this way are related to the difficulty of deforming woven or layered fibrous materials, which generally requires individual fibers slipping against their neighbors, which is all but impossible even when the matrix material is melted, as melted plastics tend to remain very viscous, and which unlike metals cannot simply be stretched by a big die (and lots of pressure). Consequently, gentle curves are possible, while complex shapes tend not to be.
Another approach involves making twills consisting of commingled strands of the reinforcement (carbon) with strands of the matrix, and weaving the result into cloth. Because the cloth can then be deformed (to the shape of the finished part) while dry, a much greater range of shapes is possible. When heat and pressure are applied, the strands of matrix melt and 'wet out' the carbon. The problem with this method is that in order to insure low porosity in the finished product, high vacuum and high pressure are generally needed, so tooling costs tend to be exorbitant.... and cycling times are not necessarily much faster than a good fabricator doing a hand layup.
William 10:09AM (9/04/2009)
The ATR group in Italy have made the carbon fiber bodies of F1 cars, MotoGP bikes, the Maserati MC12, Alfa 8C, Audi GT frame, helicopter body parts etc etc....
http://www.atrgroup.it/old/eng/storia.htm
I think the Alfa 8C sells for £100,000
http://www.autoexpress.co.uk/carreviews/firstdrives/203232/alfa_romeo_8c.html
jpm 9:05PM (9/03/2009)
"Prodigious weight" = SUV?
Umm, aluminum is very easy to machine compared to steel. Not sure about stamping/forming/forging it.
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Satn 2:06AM (9/04/2009)
He ment it terms of repairing. And machining isn't mass production for most car parts (almost everything is forged/rolled/stamped)
And aluminum can catch fire if welded improperly
Doug 3:41AM (9/04/2009)
Yes aluminum is easy to machine, but it's difficult to weld (mainly because of it's high thermal conductivity). The extruded Al frame of the Lotus cars is epoxied and riveted. Yes, it's easier to glue than weld.
bill 12:36AM (9/04/2009)
Ask Boeing and the now former CEO of that division. The new Dreamliner is falling apart in little shavings, de-laminations, etc. Now 2 years behind schedule. Sounding iffy every day.
Layering is not working out well.
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Mental Issues 11:25PM (9/06/2009)
There are a number of other reasons for the 787 not being on schedule, but it is true that its use of carbon fiber has added a lot of complexity to the development process. Not that it can't be done, though - Hawker Beechcraft builds some of its business jets with carbon fiber fuselages.
nic 7:39AM (9/04/2009)
Hi people!
That's true, standard processing methods are not suitable for mass production... let's face it: F1 cars, planes, sporting goods are all made with technologies dating back to medieval times (ok, almost: let's say, dating back to the 60ies)!
Material costs are high, indeed, nevertheless you can buy carbon fibres (e.g. standard HT) for less than 25 USD/kg today.
The biggest obstacle for mass production are really the intrinsic long processing time: thermoset resins have to cure, and for high-tech applications you need at least a couple of hours in an autoclave (a big, expensive oven and pressure tank).
There is indeed an alternative to thermoset resins: thermoplastic materials! Carbon fibre reinforced thermoplastics, for example:
-can be processed very fast (cycle time of minutes instead of hours)
-can be 100% recycled
-are significantly tougher than thermoset (thus improving crash properties)
The biggest drawback is the lack of suitable manufacturing methods, unfortunately, and the required investments. Nevertheless our company (yes, let's make a bit of marketing! :-) kringlan composites (www.kringlan.ch) develops new manufacturing methods for thermoplastic composites, and our first projects points out a significant reduction in cycle times and costs, compared to thermoset!
Best Regards,
nic
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David Martin 8:53AM (9/04/2009)
As both a comment on this article and a suggestion for a future one, I would like to mention basalt fibre.
It is nearly as strong by weight as carbon fibre but costs much less, being nearly as cheap as glass fibre.
The EDAG concept car is based around it.
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Jim 12:21PM (9/04/2009)
So if it can splinter into small shards and thus isn't suitable for body panels, what about using it for the chassis?
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Ray 12:45PM (9/04/2009)
The Aptera is possibly made from carbon fiber.
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sick o jiggy 2:10PM (9/04/2009)
What is wrong with using plain old-fashioned fiberglass like the plain old-fashioned Corvette?
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Nateb123 5:38PM (9/04/2009)
Safety. I saw a Corvette rear-end a Ram at a stoplight once. The fiberglass was crushed and shredded so bad the car had lost half of its length. There was basically a truck pushed up against an engine, pushed up (thankfully not too much) against a frightened driver. The fibreglass doesn't do much so all the force ends up directed to the engine, suspension, steering, and pedals. All of which start heading towards the driver, which is very uncool.