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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.



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.



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.


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    • 1 Second Ago
  • 31 Comments
      • 5 Years Ago
      Carbon fiber is an idea whose time will never come for automotive mass production. Catastrophic failure and non-recyclability are its two nearly insurmountable problems. I was surprised that the Rocky Mountain Institute got into being such a promoter of carbon fiber. Their mistake was taking standard automotive morphology as read and then trying to reduce weight through the use of composites.

      The problem, as some European commenters have hinted at, is morphology. We use the wrong tool for the task. Seven-eighths of the time a car has only the driver as passenger. On average, in America, we use 4,000 pounds of machine to move a 200 pound payload. That's crazy. Changing the shape of the vehicle so it can still fulfill its primary task of light duty commuting service can result in weight reductions of 50% while still being build out of good old inexpensive, strong but crushable, recyclable steel.
      • 5 Years Ago
      @Green Destiny
      Yes and no - I'm assuming you're American, which is presumably why you've focussed on the benefits for and SUV / Minivan, which you indicate are greater than for a smaller car. I'm European, so even a 1700kg car seems heavy (god forbid 2t+.) I'm objecting to the fact that here, even modest cars can now quite commonly come with SatNav, electric folding mirrors, and a whole host of other toys that I don't need, add weight and are frankly just something else to go wrong. The Golf V GTi weighs literally twice as much as models in the Golf I range - that's not all crash structure and airbags.

      Really not trying to sound pious or superior, but I just don't get big vehicles - especially when it's an SUV or minivan. Be honest, how many people actually NEED something the size of an Explorer as opposed to how many own something like it? Maybe we should be questioning that purchasing habit rather than enabling it by using expensive, dubiously green materials to make it (slightly) more palatable.

      As with my main objections to CF itself, I would really appreciate some hard data concerning this.
      • 5 Years Ago
      "Prodigious weight" = SUV?


      Umm, aluminum is very easy to machine compared to steel. Not sure about stamping/forming/forging it.
        • 3 Months Ago
        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.
        • 3 Months Ago
        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
      • 5 Years Ago
      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
      • 5 Years Ago
      The Aptera is possibly made from carbon fiber.
      • 5 Years Ago
      Fabulous stuff, but utterly un-mass-producable, so far as I've heard.

      Is anyone working on the volume production issue?
        • 3 Months Ago
        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.
        • 3 Months Ago
        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.
        • 3 Months Ago
        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.
        • 3 Months Ago
        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.
        • 3 Months Ago
        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
      • 5 Years Ago
      So if it can splinter into small shards and thus isn't suitable for body panels, what about using it for the chassis?
      • 5 Years Ago
      Interesting piece, but more a debate starter than useful reference.

      When I saw the title, I thought 'At last, some hard data about CF', but disappointed that aside from a few generalities there wasn't actually much solid info. Personally I'm uneasy with the idea of CF as a panacea for many of the reasons you touch on - it takes a significant amount of energy and some pretty nasty chemicals to produce the CF cloth and resin, even minimising waste when cutting the cloth, the offcuts aren't good for much more than landfill. The piece you actually want to make has to then be baked at seriously high temperature and pressure (some of the temperatures involved in the process are higher that the melting point of steel AND aluminium), and if you get it wrong, it's again no good for anything more than landfill. During it's working life it's stronger by weight than anything else, but in an emergency, it's failure mode is catastrophic, components can only be replaced not repaired, and the replaced items are yet again only good for landfill.

      I particularly don't like it's catastrophic failure mode, which is why although I wouldn't mind riding a CF frame bike I've never invested in a set of CF handlebars or seatpost: these are not the best applications for this material. re: bicycle frames, Trek has the OCLV (Optimal Compaction Low Void), and others have equivalents, but some of the defect rates elsewhere are shocking - I've seen photos of heaps of reject bike frames which have consumed a lot of energy but are now nothing more than landfill.

      You also repeat one of the half truths about aluminium - it DOES take more energy to extract it than steel, but it takes ~5% of that energy to then recycle it. Greater demand would surely up the recycle rate from it's current 30% or so?

      Comparing actual steel and aluminium recycling against possible CF recycling is a little disingenuous; in this case 'isn't so easily' actually means neither a process or an infrastructure exists, and anyway wouldn't the product be a lower grade material compared to virgin CF, as is the case with thermoplastics - but NOT steel and ally.

      I'm perfectly happy to be proven wrong; my prejudice arises from a dislike of something that is basically single use and unrepairable - somewhere in the wider CFRP family might be a material that addresses these issues, but please could we have some hard data?

      Maybe a direct comparison for a given component, say a body panel or chassis component? How much does this weigh in steel, ally and CF, what energy input this represents (assuming virgin metal, as CF is by definition virgin), and end of lifecycle

      Finally, the whole argument for using CF is weight reduction, and you refer to the 'prodigious' weight of modern automobiles. Contemporary cars DO have to pass more stringent crash regs, but the body-in-white is not where most of the weight has been gained - it's all the gizmos featuring electric motors and consumer electronics and the like.
        • 3 Months Ago
        Not sure if I can completely agree with you on your last comment about body in white weight. Increasing safety standards have required many of the changes to large vehicles we have witnessed recently, and have a great deal to do with increased weight (see 8 airbags, in-door protective cross beams, etc. Notice how high the belt line of a car must now be- that is primarily for side impact protection, which in turn is driven by the large number of high riding vehicles on the roads. Overall average height of vehicles is also increasing. Both of these factors create a larger body in white structure, which in turn weighs much more- because it takes much more material to make a large open body rigid (unibody SUV or minivan) than it does a small body.

        Many of the safety additions in most cars have to do with dealing with high mass incursions, like high tensile steel door beams, or 8 airbags, or rollover/roof crush protection. All of these factors add significant weight to modern vehicles. Imagine if you were able to create a minivan or crossover SUV's body in white out of carbon fiber or basalt fiber. I think one could reasonably expect to reduce a vehicle curb weight from 4500 to 3800 pounds, as the weight of other parts of a vehicle increase as the overall weight of the increases. Brakes are a good example of this phenomenon.
      • 5 Years Ago
      Besides the production time and therefore additional need for additional moulds I believe that too many are in love with the material without really understanding it. Carbon fiber is a wonderful material and in certain applications it is the right choice. Too often it is picked just because it is thought to be better or because it symbolizes top technology.
      Carbon Fiber is often not cost effective. Carbon fiber is essentially non recyclable which in the energy starved and global warming future should be a serious consideration.
      We are for all research and development but a word of caution: Carbon fiber is not easy to work with and you should know what you are doing (see Boeing problems - and they know what they are doing). Carbon fiber does not like to be joined to other materials and that is a subject that should be handled with care. I would not be surprised if the two Airbus crashes (Queens) and the Atlantic in Brazil will ultimately be traced to the failure of the joint of the carbon fiber fin to the aluminum substructure (actually the Queens one was traced to that but was blamed on too much rudder from the pilot at starting speed??). I must be clear that is only a guess.
      Anyway in my opinion on cars there is a lot of much lower hanging fruit. Weight needs to come out but weather you take out 200 lbs by doubling the cost of the car or by being smart about other parts seems to me an easy choice (and the one car makers have made so far). What should be done is that cars should get taxed by weight. This could be an incremental way of pushing product planning in a more energy conserving direction. If there was a tax on weight (starting with the overweight ones) and a tax break for low aero drag models in time the mpg would come. I am not a political person but I remember this guy named Ross Perot who said he would favor (around the early 90s) a 25 cent per year increase in the gasoline tax and spending that revenue on R+D. I have a feeling that, if that had been done, we would not have seen $4.-- gas last summer, we would not have as many environmentally irresponsible SUVs and we would not have seen the bankruptcy of two of the big three (and the foreign sale of one).
      Here is a second chance to go in the same direction without pushing the pocketbook of the American consumer who can not afford it today. We will never be competitive with the rest of the world if we do not start pushing toward energy efficiency. Not doing this provides an environment that is set up to fail in the end.
      Carbon may be partially part of that solution but I doubt it will be a carbon chassis in mass produced cars.

      Oliver Kuttner
      • 5 Years Ago
      Carbon fiber can also be made from waste agriculture products such as straw, which allows it to be recycled and less toxic to work with.
      I believe it is Nissan that is working to make a fast curing CF.
      • 5 Years Ago
      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.

        • 3 Months Ago
        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.
      • 5 Years Ago
      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.
        • 3 Months Ago
        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.
        • 3 Months Ago
        You might have mixed up Carbon Fibers with Carbon Nano-Tubes.
        The latter have given rise to concern similar to Asbestos-induced lung cancer
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