Interesting article on carbon fiber: http://arstechnica.com/science/2015/02/the-wild-weird-world-of-carbon-fiber/1/
Why can’t we 3D print this yet? Wait, somebody is trying that: https://markforged.com/
I see some filaments are out there also. Anybody experience on it? Still a long way to go, or can we start to experiment ourselves on a prusa i3…
http://arstechnica.com/science/2015/02/the-wild-weird-world-of-carbon-fiber/1
It’s unclear what Mark Forged is actually doing, and if it’s real, how they’re doing it.
@Jeff_DeMaagd Looking at their promo, they use just a reel. So supposing it is something like http://www.3dxtech.com/high-modulus-carbon-fiber-abs-3d-printing-filament/
they have abs filled with carbon fiber, and extrude it. During extrusion, the fiber and abs mixes, and is heated. So perhaps the abs or pla acts then as glue needed for the composite.
Main question then is how the curing happens. If this curing is just the heat of the nozzle, I don’t understand how they can avoid nozzle blocking when the carbon fiber nozzle has not been used for a while.
Reheating would melt the ABS, but the carbon fiber would be cured, and hence harder than what you want …
They are not using fiber filled materials, which implies that the fibers are short, chopped, and not particularly oriented in a specific direction. From the videos it appears they are using continuous roving (or tow). Additionally, I do not believe they are using thermosets (which is where the “curing” come sfrom) I believe they are using thermoplastics.
While it certainly seems to be a novel machine, the practical uses of it escape me. Composite parts are inherently weaker perependicular to the layup, similar to how FDM parts are weak in the build direction. However they differ in that traditional composite manufacturing techniques allow the properties to be molded (so to speak) around the geometry. Whereas when 3D printing your laminate effects are going to always be in the build direction.
A simple example is an L bracket. To get good performance out of it it must be printed on its side. There’s really only one orientation to mold such a bracket. While the overall geometry of the bracket would be strong in both cases; in the 3D printed version it would be susceptible to splitting where the fasteners penetrate. The molded version would have continuity to resist the pullout of the fasteners while still performing well in terms of how the overall part is intended to be used.
To combat the pullout issue we can try to turn the bracket so that one side is in the x/y plane and the other is in the x/z or y/z plane. The pullout issue is solved on one side of the bracket but the properties of the geometry have been decimated while still having a pullout issue on the x/z or y/z side.
2 different animals. One lays down a unidirectional tape of uncured pregreg. Once the part is completed, it gets vacuum bagged and cured in a high pressure autoclave. Markforge is just a 3D printer. The filament might be different, but the machine itself and the process is nothing like the one in the article.
I’ve seen the mark forged in person and talked at length with a couple of the guys. The most interesting guy was the guy that wrote the software / firmware. They are super secretive but they will show you pets they made. Brian and I looked at the parts and it renders an incredibly strong part. Not good for everything but really good for some things.
Basically, they have two heads. One extrudes a continuous string/weave? of plastic-encased carbon fiber (or what have you). It lays down a layer of that in a neat spiral shape or whatever-- all in one layer. this is where the custom software blows my mind. Then it cuts the string and moves to the other extruder for regular plastic.
Really neat. Really patented all to heck.
Did I mention they are super secretive… They remove critical parts, cover things with black cardboard, never show it printing… Drives me nuts.
Brook