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World’s First Carbon Fiber 3D Printer Announced

3dprint.com

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Re: World’s First Carbon Fiber 3D Printer Announced

#11

Post by MechSkep »

542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

I'm skeptical too, but don't count it out because the fibers aren't woven together. The weaving is not where the strength comes from, and it's usually not omnidirectional. If this machine can set the wrap angle, and build out several layers, the fiber layout might be comparable to a filament winding process. http://en.wikipedia.org/wiki/Filament_winding

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.

Re: World’s First Carbon Fiber 3D Printer Announced

#12

Post by zevets »

MechSkep wrote: post #11
542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

I'm skeptical too, but don't count it out because the fibers aren't woven together. The weaving is not where the strength comes from, and it's usually not omnidirectional. If this machine can set the wrap angle, and build out several layers, the fiber layout might be comparable to a filament winding process. http://en.wikipedia.org/wiki/Filament_winding But the thing that I'm concerned about is the curing of the stuf…

Looking at the specs page, their claimed yield stress is 20% higher than aluminum compared to a factor of ~4x for traditional CF composites.

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.

Re: World’s First Carbon Fiber 3D Printer Announced

#13

Post by hershel »

542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

Maybe the issues you raised cause it to only "3D print parts that are stronger than CNC machined aluminum by weight."[1], according to the company, and not stronger as carbon fiber.

[1]http://www.3ders.org/articles/20140128-markforged-mark-one-w...

Re: World’s First Carbon Fiber 3D Printer Announced

#15

Post by Florin_Andrei »

542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

> The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally.

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.

Re: World’s First Carbon Fiber 3D Printer Announced

#16

Post by Gravityloss »

kyrra wrote: post #9

The allure of carbon fiber in industry has to do with the properties of the material that can be produced. Home made carbon fiber won't be all that great of a material compared to what people see out in the world (on race cars, planes, etc...). Production lines for producing commercial carbon fiber is super expensive ($100 million+). Zoltek has a basic rundown of the process [0]. [0] http://www.zoltek.com/carbonfiber…

For the really good stuff, you'd need pultruded carbon fiber where the glue sets with the fibers tensioned straight to really get good strength effects.

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...

Re: World’s First Carbon Fiber 3D Printer Announced

#17

Post by morcheeba »

jaydub wrote: post #7

Are there health risks associated with extruding carbon fibers? I was under the impression that working with carbon fiber can be potentially harmful to your health.

There are two types of risks:

- 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...

Re: World’s First Carbon Fiber 3D Printer Announced

#18

Post by Retric »

Florin_Andrei wrote: post #15
542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

> The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally. 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 fi…

It depends on the load, for a bullet poof vest you need to have woven threads, for a cable it's less of an issue but weaving still helps once the threads start breaking.

Re: World’s First Carbon Fiber 3D Printer Announced

#20

Post by grmarcil »

batoure wrote: post #8
542458 wrote: post #2

Count me as skeptical. The strength of high-quality carbon fibre comes from having many pieces of fibre woven together over the surface omnidirectionally (Okay, I'm mostly wrong here - see below). This machine seems to simply lay it down in a (more or less) continuous strand, which means that the fibres will be cohesive rather than woven together. You can do this without a special printer - all you need is some carbo…

I think that this is more of an 80 20 kind of question. At this level the argument isn't "hey this is as good as carbon fiber" but "hey this is better than regular 3d printing filament"

I agree in part, but I think you're overlooking a big tradeoff here. Printing with plastic filaments gives you a fairly weak piece, but leaves open the door for a lot of post-printing finishes (surface smoothing, using the piece as a positive image to invest, melt out, and cast as metal, etc). You give up a lot of those opportunities printing CF strands, so this printer really does need to be able to produce pretty strong parts to have a competitive advantage big enough to offset those tradeoffs. It definitely does not have to achieve traditional carbon fiber strength to be worthwhile, but it needs to be considerable.
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