For a pretty freaking cool view of how high-quality carbon fibre parts are made check out this youtube link: https://www.youtube.com/watch?v=l4DLr8qHliI
[1]: https://www.kickstarter.com/projects/1375236253/proto-pasta-...
[2]: http://www.makerfarm.com/index.php/2-2lb-1kg-1-75mm-clear-po...
No, not at all.
The strength of CFRP (carbon fiber reinforced polymer) comes from having very long strands of carbon fiber, ideally as long as the whole piece, held together by some polymer matrix such as epoxy resin. It also comes from having a very high fiber-to-epoxy ratio in the final product, which is usually achieved by squeezing out all the extra epoxy using vacuum while curing.
The length of the fibers, and the minimal amount of epoxy, is what makes CF strong. Short fibers, and having too much epoxy matrix, weakens the composite.
There is a kind of extruded CF where short CF fibers are mixed with epoxy matrix and extruded in the desired shape. This is strong compared to ordinary plastic, but not as strong as long-fiber CF.
What you're describing is woven CF, and it's not the strongest there is. The strongest CF pieces are made of unidirectional CF, where all fibers are oriented in the direction of the main effort. E.g., CF tubes are strongest when they are made of unidirectional CF, with fibers as long as the whole tube.
Woven CF is a good compromise in that it's reasonably strong in several directions in the plane of the CF cloth. Also, for CF tubes, an outer layer of woven CF gives it a bit more resistance to splintering.
Another way to achieve multi-directional strength is by laying unidirectional cloth alternatively in different directions. The piece will gain strength from each unidirectional layer in a specific direction.
Most people recognize the classic "CF look" only when the top layer is woven. Unidirectional CF cloth has a different look. This is why many CF items are made of unidirectional cloth, with a single woven layer on top.
If this CF 3D printer can lay long-fiber CF, and can achieve a very high fiber-to-epoxy ratio in the final product, then chances are the pieces produced this way will be strong.
You're confusing issues even further! To anyone who wants to actually understand this:
Carbon fibre doesn't have a single "strength" value since it is virtually always anisotropic - its strength varies massively depending on which direction you stress it in.
GP is correct in that the carbon fibre weave with the best minimum strength is the 3D woven stuff which is very fancy and difficult to make, and not what this printer makes.
The most common carbon fibre is 2D woven cloth which is laminated together like plywood. It is strong in the directions of the fibres but can very easily delaminate (the layers become unstuck). It's a pretty big problem for things like the Boeing Dreamliner because the delaminations can be under the surface and impossible to see.
CFRP tubes are often made with the fibres all running along the axis of the tube, but it is then extremely weak in the circumferential direction and will tend to split like bamboo.
The incredible strength of carbon fiber comes from the
long, continuous strands that carry load down the entire
part. This is why space shuttles, rockets, and Formula 1
cars are constructed from continuous strand carbon. And
it’s how we print. Don’t settle for plastic with a dash of
chopped carbon fill. Longer is stronger.
-
7mm x 3mm x 100mm. 3D Printed beam is packed with tens of
thousands of full length, continuous carbon fiber strands
And how do you even cure it? Is it just carbon fibre in a thermoplastic matrix?
But the thing that I'm concerned about is the curing of the stuff. A composite gets its strength by having a low resin content, and I'm not sure this machine/process can pull it off. Based on the few available details, it's right to be skeptical.
Also concerns about the fiber content may be misguided. The hard part of CF compoisites is the the layup process, which is what a 3D printer would do. The part can then be vacuum bagged to pull out the resin, as in traditional CF manufacturing techniques.
Besides needle-punching, there are a bunch of other non-woven technologies that I reckon could be applied to carbon fibers in some form.
[1]http://www.3ders.org/articles/20140128-markforged-mark-one-w...
Do you still need to Autoclave parts created by this printer?
A lot of composite work is low volume production with excessive manual work at not very good quality.
Ultrahigh Molecular Weight Polyethylene (UHMWPE) might be a much more interesting material as it has a higher strength to weight ratio and as it melts at a lower temperature, 135 C. It is nontoxic too.
http://en.wikipedia.org/wiki/Ultra-high-molecular-weight_pol...
https://localmotors.com/press/releases/vehicle-design-innova...
I've also been giving some thought in starting the worlds first 3D printed furniture store.
Product site, video, tech specs, pre-order, etc.
- epoxy sensitivity. Work with it too long (years) and you can become allergic. I can't tell if this system uses epoxy as a binder; it doesn't seem to because it would be messy.
- inhaling carbon fiber dust. This dust is made when you cut it, not when you lay it out. A 3d printer should put it in the right shape, so less cutting would be required. You'll want to avoid breathing it in, but it's not cancerous like asbestos: http://annhyg.oxfordjournals.org/content/38/inhaled_particle...