Why are vehicle manufacturers are moving away from carbon fiber??

[pantelis182]

Hello

Reading this article about Ferrari

http://www.sae.org/mags/SVE/10391

“Some niche vehicle manufacturers are currently moving away from carbon fibre components for their medium production volume vehicle structures because of long processing times needed for high integrity carbon fibre composite components”
I'm trying to understand the reason why this is happening?

 

[BrianPetersen]

It means the time that it takes to manufacture a carbon fiber part is too long for that part to economically be made at the production volume that they are looking for.

If the new vehicle design is expected to sell in higher volume than the old one, and it's beyond that production-rate threshold, then you either substitute a different material or you double the cost of the tooling so as to run two in parallel all the way through or you deal with the production-rate limitations.

Carbon-fiber parts have to be cured in-mold, which ties up that mold for the duration of curing. Sure, you could have multiple molds and do multiple parts at a time ... but that gets expensive, space-consuming, and time-consuming. The production method for carbon-fiber or fiberglass parts lends itself to low-volume production, but it's not like steel stamping where you shove a set of dies into the press and whack out one every couple of seconds until you have a bunch of left fenders, then swap dies and use the SAME press to knock out a whole bunch of right fenders, then swap dies again and use the SAME press to knock out a bunch of door skins, etc. Or injection molding where you do the same thing using dies for an injection molding machine - those won't do as many cycles per minute as steel stamping will, but it's still within reason.

 

[pantelis182]

In this stage manufacturers (FERRARI) claim that using this moment carbon fibre in car industry is not that profitable as aluminium beacause the methods are of manufacturing carbon fibre parts has not fully been maximized?! . If that is so Ferrari is giving up better strength to weight ratio to make a better profit?

 

[GregLocock]

There isn't much benefit in stiffness to weight for many components from carbon fibre. In production cars, and especially high end sportscars it is mostly used for styling and marketing. CF is not a particularly good material for most parts of a car.

Even on racing cars some F1 teams have been known to use steel suspension arms with a carbon fibre applique over them.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[MikeHalloran]

In order to survive, Ferrari has to make a profit; that's fundamental. They can't be making any money on F1, and not much on hand built supercars.

Medium volume production, in the order of magnitude of 30 units a day, is tough to make profitable, no matter what the units are.

Carbon fiber part production is now a pretty mature technology; it can't go faster; it's already been optimized, for several different processes.

The article says that they can't make parts that are dense/thin enough to meet their internal standards with prepreg, which is adapted for medium volumes.

They can make thin/dense parts with resin transfer/infusion molding, but that produces huge quantities of waste per part. Filling many dumpsters per day with plastic sheet and tubing contaminated with resin is very much politically incorrect in Europe these days, so they can only justify it for low volume production.

Hence, they fall back on aluminum, which for Ferrari is very much a known and mature technology. Well, aluminum and Bondo, so I hear.





Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

Well at least they don't just mig weld square tube together and call it a chassis

http://carbl.com/im/lambocrash2.jpg

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Compositepro]

Carbon fibers have some unique and very impressive properties, but there are few parts that I would choose to make from it. What makes carbon unique is it's relatively low density combined with a Young's modulus equal to or greater than steel (fiberglass is as strong as standard carbon fiber, but weighs 50% more and has 30% of the stiffness). It is extensively used already where there is a clear technical and economic benefit - aerospace and fishing rods.
Stiffness can be obtained by geometry as well as material properties. A major problem with carbon fiber is making very thin sheets because multiple layers are generally required to make a quasi-isotropic layup. Sheet metal can be very competitive because it can be made thinner and shaped more easily. Where low weight is the the most critical factor, carbon has little competition. In the real world there are many other imortant factors such as cost, repairability and damage tolerance. If my F-350 weighed less I could not tow as much weight. Light cars will take the brunt of any collision.

 

[140Airpower]

Gee Compositpro, what do you tow with an F-350? Oh, I get it. It's interchangeable with a Ford?

 

[dgallup]

http://www.compositesworld.com/columns/automotive-carbon-fiber-seeking-moderation

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[yoshimitsuspeed]

BrianPetersen
You are forgetting one form of composites that is ideally suited for high volume production and that is thermoplastic composites. Very similar to stamping sheet metal you can move parts through very fast. In some instances a forming each minute or less. Just like with sheet metal the downsides are initial development, design and tooling costs. For high volume projects it's very economical. Another big advantage is that you can recycle the scraps and even the parts and form them into another composite part.
This technology is already being used by many big car companies, aerospace and military but it definitely has it's quirks, problems and need for further development.

With that said, I think that article explains it very well. Even with the rapid forming and ease of production that thermoplastics can offer it is still going to be more expensive and more challenging to work with.
You can "weld" thermoplastics using very expensive equipment but are very limited in how and what you can do.
High quality material is generally going to cost more than metal.
Unless the strength to weight gains warrant the cost there is no reason to do it.
On a mid level street driven car spending another $20k to save 20 lbs just may not be worth it.

One other thing that I suspect is that it may be more than performance.
Carbon fiber and kevlar first came out and it quickly developed this obsession from anyone the least bit interested in performance. It was a magically light and strong material that no one could afford and everyone wanted. As it became more accessible it blew up. This meant that people could sell things with carbon fiber in it for a lot more money than something without it.
We used to work next to a company that made RVs. They put a single layer of Kevlar in their bumpers so they could say they were Kevlar reinforced. It wouldn't be enough to make any notable difference to anything but to the consumer it was the coolest thing ever. Same goes for most carbon fiber hoods and most other cheap affordable "Carbon fiber" parts. Usually fiberglass with one layer of CF that sells for three times the cost and 100 times the quantity than it's all fiberglass counterpart.

I hate to say it but I'd be willing to bet that even companies like Ferrari saw the money potential in this fad and it had very little to do with it weighing 20 lbs less. It was being able to say it weighed 20 lbs less because it was made out of Carbon fiber.
As fads do they start to fade out or work their way down the food chain.

 

[BrianPetersen]

Of course, thermoplastics with random chopped fiber reinforcement can be processed faster ... but that's not oriented-strand carbon fiber! And the fiberglass parts that I'm talking about are those made using the lay-up and resin process, thus having oriented strands.

I have a customer that makes low-volume carbon-fiber parts for certain specialty vehicles ... and another one that makes glass-fiber-reinforced (random chopped strands) thermoplastic molded panels in huge quantities. Two entirely different processes.

And you're certainly right about fiberglass parts being made with one layer of carbon fiber just so that the marketing department can brag about it ...

 

[yoshimitsuspeed]

Ah but I never said anything about chopped strand.

A Company I used to work for.
Unfortunately poor and unqualified upper management sank a company with a great deal of potential.
99% oriented long strand thermoplastic composites.

http://www.fiberforge.com/

http://www.fiberforge.com/media/pro...This=true&TB_iframe=true&height=540&width=725

An offshot of that company.

http://www.oribimanufacturing.com/home.html

There are many others in this field with a heavy focus on the future of auto, aero and military.

 

[tbuelna]

Automotive OEMs have not "moved away" from using carbon composites. Instead, the reality is that they have never used carbon composites, except for a few limited applications. As others noted, the biggest hurdle is manufacturing cycle times required for laminated carbon composite components.

Consider this: for a low production car model you might need to produce 50,000 carbon composite fenders in 10 months. That works out to 165 per day, working 24/7. If a single fender takes 4 hours to lay-up and cure, that would mean you need 27 sets of tooling for producing those fenders. Definitely not practical.

 

[dynatune]

As with many things the world is continuing it's developments in every area of mechanical engineering. Carbon has still a massive advantage in weight to strength ratio (and costs) but that comes largely into play on parts that are important for carrying loads. Obviously making a rear view mirror has somewhat limited cost over function ratio .....I am not even talking about production cycles and so on .. the most "advanced" companies that create and sell carbon fiber chassis cars can only make 5 a day.

Beyond that the "classic" materials and in this contest in particular "Steel" keeps on making continuous progress. One can now almost get super strong steel tubes off the shelf with amazing strength bringing back to "life" very ancient classic engineering approaches that have been cost optimized for decades. It seems that increasingly this new awareness is spreading around the automotive world with all due consequences for the once be-hailed CF.

Cheers,
dynatune,

http://www.dynatune-xl.com