| Blown353 |
10-25-2022 08:13 PM |
Doing work with aerospace composites on a daily basis, I find it funny how various places have managed to rebrand chopped carbon fiber molding compound as "forged" carbon fiber and now often charge a premium for it when for decades chopped fiber compound has often been made from the trimming and off fall from the weaving and fabric or unidirectional prepreg production process that would normally be thrown away. Now, rather than paying hazmat fees to dispose of the stuff that pretty much nobody wanted, they've given it the fancy name "forged carbon" and can make parts with it and sell it for a profit!
We fabricate a few press molded chopped carbon fiber "cup and cone" type inserts for very small satellite solar panel launch locks along with other small or lightly stressed fittings, and the carbon prepreg companies that we buy the chopped fiber molding compound from sell it for substantially cheaper than prepreg unidirectional or woven carbon fiber fabric as the chopped fiber is literally the trimmings, fall off, and sections of distorted woven fabric or uni that they normally can't sell-- so they chop it up into small bits, mix it with resin, and sell it for molding compound.
Of course, if you want a uniform look for cosmetics for this so called "forged" carbon fiber they normally chop up a batch of identical carbon tow so all the chopped pieces look similar rather than the "whatever fell onto the floor" look that we use for some of our molded parts.
It does look different for sure, and because the fiber lengths are so short and the fiber directions can't really be oriented in specific orientations because of the very nature of the chopped fiber molding compound the strength of the finished part is weaker than a controlled layup using unidirectional or woven fabric where the orientation of the fibers in every ply can be controlled for the desired strength in the finished layup.
"Forged" carbon is usually faster and cheaper to fabricate as you don't have to spend the time carefully cutting, orienting, and placing woven or unidirectional carbon fiber and make sure there are no wrinkles that will diminish the cosmetics as you would have to do with a normal layup-- with the molding compound you can just scoop it out of the container, pack it into the mold, and cure it. Quite a bit less labor, and also less of it goes into the garbage as you don't have to deal with trying to nest each ply of the part as efficiently as possible on a roll of material so as not to waste material as you do with unidirectional or woven fabric.
I see it as a case of "marketing at its finest" -- turning what would typically be scrap into profit with a fancy new name and some cool pictures for people who want something different.
For a cosmetic piece, I see no issues with the chopped fiber / "forged" stuff if that's the look you're going for. For a highly loaded structural piece, give me a traditional unidirectional or fabric oriented layup any day of the week. I've never seen a critical structural piece on an aircraft or spacecraft made out of chopped fiber if that says anything...
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