'Forged Carbon Fibre' in F1?

[RicerDude]

Not very knowledgeable on the subject of composites so please excuse me. As far as I'm aware forged carbon fibre is made in a similar way as cold forged metals, to align the crystal structure in a single direction for better strength. Is this not the same idea as normal carbon fibre? Mats are layered in different directions to achieve the same desired effect.
So part 1 of my question: is forged carbon fibre actually superior to normal carbon fibre? Or is it just marketing bs?
Part 2: if it so great why do we not see it being used on every non metallic part of an F1 car?
Many thanks,
Harvey

[graham.reeds]

Marketing BS imo though it does have a couple of advantages over regular layered cf. The marketing at the time said it was an effort between Calloway golf clubs and Lamborghini.

If I remember correctly you have biscuits of impreg (so the length of cf is short) and these biscuits are then compressed and cooked. These pieces are then glued or bolted together. The resulting pieces are lightweight but not as structurally strong (despite marketing) as laid cf but are significantly quicker to churn out. Ideal in a mass produced vehicle/item. Not really for a 1 off race car that changes significantly.

My memory could be cooked as it has been many years since I had heard of it.

[gambler]

There may be a technique to that, as it is usually vacuum bagged and heated that way to cure. It may would be plausable to forge it to achieve a perfect resin to fiber ratio. I can't imagine it being forged post cure. Then again I'd never say never....

[e36jon]

This is one of several 'closed mold' techniques for making carbon fiber parts. (Easton makes carbon bicycle stems using an 'injection molding' like technique, which is different but achieves similar results.) My understanding is that it needs matched metal tools to 'forge' the shape, and then cure said shape inside the tool. So, no vacuum bagging / autoclave to the best of my knowledge. And so greatly reduced waste and hand labor.

These parts have relatively short fibers and only achieve 'some' alignment during 'forging'. A part made using other aerospace grade techniques (Filament winding, tape laying or hand layup of prepreg.) will greatly exceed the mechanical properties these forged parts can manage, but at a huge increase in cost due to all the hand labor and waste.

As was pointed out, due to the constant change in F1 everything tends to be 'handmade' using prepreg fabrics. They make tools, but usually using epoxy tooling board, not matched metal. Even so, I look at a front wing and wonder how they make some of those parts...

So, no, I don't think forged carbon is being used in F1.

[Maritimer]

The OSB of carbon

[Tommy Cookers]

cfc question .......

presumably the vacuum method purges air 'bubbles' that otherwise could trapped in the resin
can this trapping occur with prepreg ?

years ago some people died when this caused some 'Russian' aerobatic planes to lose their wings

[trinidefender]

From my understanding forged carbon fibre is a variation with compromises (as most materials are). Compared to normal pre-preg carbon fibre sheets:

Pro's:
- Rapid and cheaper to produce
- able to do more complex shapes than normal sheets

Con's:
- generally not as strong

Not sure:
- puncture resistance?
- flaw tolerances?

[Greg Locock]

presumably the vacuum method purges air 'bubbles' that otherwise could trapped in the resin
can this trapping occur with prepreg ?

Yes, you have to vac bag prepreg, and use a bleeder layer, otherwise your resin ratio is ridiculous.

[trinidefender]

presumably the vacuum method purges air 'bubbles' that otherwise could trapped in the resin
can this trapping occur with prepreg ?

Yes, you have to vac bag prepreg, and use a bleeder layer, otherwise your resin ratio is ridiculous.

People are always surprised when they see weight differences with carbon fibre between relatively the same thing made by 2 different manufacturers when they think carbon is carbon. Resin is probably the heaviest part of the whole process. And all excess should be removed either during the process or sanded off after.

Source: worked for a guy who built carbon fibre boats and other parts for a few years.

[johnny comelately]

Hey Rdude, are you talking about the carbon fibres themselves or the composites using them?
If the fibres, there are some processes that align the crystals (I will get shot at here) in a fashion similar to what forging does.
Otherwise its marketing BS where they take a grain (pardon the pun) of truth and spin it into the longest of yarns

Here are two very interesting links to the fibres and...:
http://zoltek.com/carbon-fiber/how-is-c ... iber-made/
https://en.wikipedia.org/wiki/Carbon_fibers

[gambler]

I've heard the temperature in which Carbon fiber finished product is cured determines how much heat it can take. Like a body panel is cured to 400degrees and say a brake rotor to 2000deg (those are just guesses) I was wondering if there is any truth to that. Also I wonder if the cure temp affects the hardness to resist bend or maybe a softer cure may allow flexability?

[e36jon]

With regards to cure temperature, it doesn't work quite like you are stating. You can't buy some resin and cloth on Amazon and then bake them at 2000 deg C and make your own carbon-carbon rotors. There's a lot more to that process.

What is true is that if you have a resin system that cures at 350 F, you can sometimes do a post-cure heat cycle at that same temp or a bit above that will raise your parts resistance to heat (The temp where it loses mechanical properties) from then on. In general, the resin system determines what the max temp range is for the part, with very high temp systems being pretty exotic, and not much fun to work with (They don't flow well.).

The final mechanical properties, to a degree, are not that dependent on the cure temp of the material. A 350 and a 450 cure prepreg, once made into a part, will not be radically different. The issue is that the high temp applications usually want different properties than the low temp, so the resins are usually really different, so in the end it's apples to oranges.

I don't want to oversell myself on here. I worked for a couple of years at Hexcel composites R&D as an engineer, but am no longer in the field.

[gambler]

Thanks E36, ....

[trinidefender]

I don't want to oversell myself on here. I worked for a couple of years at Hexcel composites R&D as an engineer, but am no longer in the field.

You're probably one of the most qualified in this discussion then.

Maybe you can assist I trying to get rid of a bit of the ambiguity surrounding this forged carbon stuff?

[Tim.Wright]

I don't want to oversell myself on here. I worked for a couple of years at Hexcel composites R&D as an engineer, but am no longer in the field.

So is forged carbon basically an evolution of Hexcel's Hexply tooling material which I came across around 10 years ago?

I've recently seen some forged carbon parts on some luxury sports cars but in non structural applications where fibre to resin ratio isn't as critical.

Using the term forged in this application is a bit of a misnomer. Forged metallic parts benefit from a compressed outer layer of material to give improved fatigue resistence. As far as I know forging a composite part doesn't compress anything, it just squeezes resin out to help the part conform to the mould so there is no performance benefit. It's done for cost reasons as it's cheaper than a manual layup.