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Discussion Starter #1
Hi I wounder if anyone know a good ressource on the web for making carbonfibre?

I was thinking of making a few small items, just wanted to read alittle about it first..
 

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Don't have a web source or anything for you...but basically soft fiber is cut (and/or placed in a mold) and layered up with epoxy. Good CF is oven cured.
 

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Roffa said:
Hi I wounder if anyone know a good ressource on the web for making carbonfibre?

I was thinking of making a few small items, just wanted to read alittle about it first..
It takes a hell of a facility to MAKE CF. If you are refering to WORKING with CF, that's much easier. You need fabric, impregnation resin, an oven, a vacuum pump and some plastic. Then you can start making molds.

-Jim
 

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CF for Roffa

Roffa -

There are many, many companies that make many, many different types of carbon fiber (CF). Because I used to work for a manufacturer in Florida for a few years, I could go on a huge diatribe on how it's made.

Keeping it simple, its important to realize that there are two very specific types matrixes of manufactured CF: thermosets and thermoplastic. The matrix is the material that holds the fibers together into its net shape; whether that be a body panel, hood, or other part.

Why is the matrix of the CF so impotant? It depends on the application you seek. For almost every application that we as drivers we would see on the road, the CF matrix will be a thermoset - usually an epoxy of some kind. Thermosets have the lowest strength-to-weight ratio, so using them just for interior/exterior parts is fine. You know its funny, after working with this material for a few years, I realize how counterproductive most CF parts are that we see on cars today: they have a very low CF volume (low strength), and a high volume of resin (high weight). Sure the polished resin look nice, but its just high-cost and ineffectual.

Better are the thermoplastics. These matrixes are more difficult to manufacture, but offer very high strength-to-weight ratios; even better than steel. This is the type of material you would see in military applications or in racing teams with huge funding.

You can get more technical information and even design your own parts with this Floridan manufacterer at:
www.AmericanMatrixCorp.com

I hope this answers some questions. Otherwise, go google searching. Good luck.
 

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Discussion Starter #5
Thanks.. I have google'd abit already, found alot of manufacturs, but not much info on how working with it.

I have a friend that can make "anything" for me, but I can't reach him now as he lives in an other country right now.

When he comes to visit I'll grab whatever information I can get...
I plan to make some stuff for the engineroom and a superstron & light carbon / kevlar "shield" to protect everything underneeth the car.

Well if anyone else know a good FAQ or HOWTO site please let me know :)
 

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CF application

Roffa -

Since you're interested in protecting your car's underbody, I might guess you're interested in rallying. Right on.

I can give you some of the manufacturing steps, but you will need to get your hands on the raw materials first - and if you take any piece of advice from me, make damn sure you get CF with a thermoplastic matrix. This is for two main reasons: One - thermoplastics can be remolded if your parts don't cure with the desired finish or don't laminate properly. Two - when finished, you will have the strongest CF material available.

Back to the raw materials. You can buy material in a number of ways from their producers. You can purchase the raw CF (very messy and a serious breathing hazard) and add the matrix (usually in powder form) during the molding cycle. The best and definately easiest way to get the CF is with the matrix in a pre-impregnated form; better known as pre-preg. The only drawback to pre-preg is its very high cost. You will find from CF producers a CF thread count - usually between 3K and 12K. The more fibers per square centimeter, the stronger it will be. Now you'll want to choose the matrix itself for your application.

For the underbody of a car, I would recommend a high-temp thermoplastic like PEEK (polyether-ether-ketone). It has a sustained service temperature above 600 degrees F - perfect for protecting the hot underside of a 4cyl boxer engine.

Once you have the materials, you will need a male/female mold cavity that can be heated and held above the thermoplastic melt point (PEEK happens to be 680 degress F). And once at operating temperature (about 700 degrees F), thin parts (1mm-5mm thick) take about 10 minutes to fully cure. Thicker parts might take as long as 30 minutes. Once the heat cycle is completed, make sure to cool below the glass-transition temperature (completely hardened) - which for PEEK is about 380 degrees F - before trying to remove your part.

Most molds I've used have been made out of aluminum or steel. This mold will also need to be held in a compression mold press at a pressure somewhere between 500 and 2000psi (depending on the part dimensions and thickness - more surface area, more pressure). And finally, don't forget to get a hold of a good solvent-based mold release agent for your tool. After all, nothing is worse than spending all that time getting material and molding a part just to have it stuck inside its mold cavity.

Long winded, huh? Not really - just some friendly advice to another WRX enthusiast. Besides, Scandinavians need to stick together. One last piece of advice - when you're in a rally, make sure you have the right pace notes!
 

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Wow. Thank you man, that's excellent information. No more fiberglass for me! Actually...can it be applied on top of a fiberglass mold as the last few layers? assuming the fiberglass can sit in the oven...
 

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Discussion Starter #8
Re: CF application

fsidesmith said:
One last piece of advice - when you're in a rally, make sure you have the right pace notes!
Yes I will..
Alittle OFFTopic, but actually I almost totalled my wrx because of wrong notes !!
I went of the [email protected] managed to clear 2 big trees as the car left the ground. It was airborne 3meters while jumping down a small slope. I hit a small tree (9cm in diameter) with the front bumper and ran it over. When I saw it coming I don't care all I tough was that it would slow me down...

Best part of it all NO DAMAGE to my car !:eek: All that happend was a broken license plate !

But it did'nt last long the day after I hit some hard snow @ about 0,5mph and scratched much of the lower oart of my bumper ;)

Well what I learned is that you should always have the right pace notes while rallying your dailydriver ! :tongue:

BTW Good writeup on the CF !!! very informative. When (if) I make something I'll let you all know ;)
 

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Actually...can it be applied on top of a fiberglass mold as the last few layers? assuming the fiberglass can sit in the oven...
SVC -
Answering your question about applying thermoplastic CF on a fiberglass mold: It depends. What is the matrix of the fiberglass mold itself? From my experience fiberglass molds, like ones used in an autoclave or vacuum-bagging process, tend to be made with epoxy resin. If this is what your fiberglass mold is formed with, you don't want to try even the lower-temperature thermoplastics in it.

The lowest temp thermoplastics I've dealt with were Nylons (and there are several different types of Nylon matrixes), which have a melt point of about 380-450 degrees F; still too high for thermosets like epoxy which is a chemical-reaction cure, speeded with heating to around 200-250 degrees F. You can heat an epoxy part (tool, or whatever) above its process temperture for a while, but after a few minutes it will likely deteriorate, melt, or possibly burn.

But lets assume the fiberglass tool you speak of is a thermoplastic composite made with PPS or PEEK. As long as your manufacturing procedures stay within the recommended heat tolerances of the matrix's producer, you can get on it and make some product!

Quick-shifting gears...so you're from Boulder, huh? I lived there from 1986 to 1995, and graduated from Boulder High School in '89. At Boulder, SWC meant Senior Women's Club. Any association there? Ah, the memories (or lack there of) of parties on The Hill...
 
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