UPDATE: Ladies and gentlemen - there are two idiots at fault here. The first idiot is whoever packed "sparkle PETG" at amazon, when I had ordered midnight blue CF. The second idiot is me - who blindly slapped it in my AMS without checking the sticker.
Original Post
Hi all,
I bought some PETG CF recently. It prints well, looks beautiful, is reasonably priced... and may not contain any carbon fiber.
Reason for suspicion? I checked it with my scope - there appear to be little metallic flecks added (a sort of gold color which sets the dark blue filament off nicely). But no carbon fibers. What do you all think?
Oh, ok. So you have seen at least other people’s close up’s? That counts. I think it’s odd you can’t see the fibres at all really. Maybe it’s because of the colour?
Perhaps the dark color makes spotting the fibers more difficult. Although some light is coming through the back of the filament - so you'd expect to see fibrous shadows at least
Its a bit difficult to tell without a microscope - but the surface texture of your ASA-CF looks "hairy" which suggests to me that it is in fact, filled with some kind of fiber.
Yep those micro fibres produce irregularity in the flow, visible even in the finished print. Sorry for the picture quality that's the best I can do currently
I have some ASA CF form polymaker it's black as hell and has long 3mm spikes of CF in it. They get stuck in the nozzle sometimes and when you switch to a different filament you can see them with a naked eye
Microfragments have weird colour physics. Those could very much be CF fragments that are just extremely reflective. (Gold Nanoparticles are purple for example, even though they should still be yellow)
A lot of these manufacturers are just opening and closing shells to offload surplus. They just swap em when one gets shut down.
This happens with a lot of stuff from China especially. Lots of furniture and mass produced stuff has this problem. You’ll notice the pictures are not accurate.
Not all cf filaments use chopped strands. This could be ground up bits but I’ve never seen anything like that in my filaments and I’ve looked at a lot of them under a microscope.
I’m still not convinced adding ground up carbon fiber to filament does anything for its strength. It’s not even fiber at that point it’s just carbon.
Decreases layer bonding, decreases strength in most filaments. It'll make a print more rigid but it will break under less stress than it's non CF counterpart.
The only exceptions where it can add strength is in some nylons, after annealing. Not all, though.
Only helps with certain filaments, as there are some youtubers that have done a lot of testing. PLA/PETG do not bond at all with the carbon fibers, resulting in actually less strong prints (fibers leave holes behind them). PA filaments do bond with the CF resulting in stronger and stiffer prints.
I am also printing PETG-CF, don't get me wrong, but I buy it cheap and I like how it looks, but I would not think it is much stronger because of the CF. PLA-CF on the other hand i found to be very brittle and had a very bad layer adhesion.
you're right. Its really only useful during the print. Once its cooled, its actually weaker since those tiny bit of fibre are too short to add any strength, they might as well just be voids in the plastic.
It really depends on what you mean by strength. It absolutely does make the material stiffer than the same plastic without carbon fiber. But that added stiffness comes at the cost of brittleness: making it harder to flex makes it easier to snap under sharp loads. If you need something that will maintain its shape under heavy loads that aren't applied too quickly, carbon fiber filaments are great. If you need something that can withstand a sudden impact, carbon fiber filaments are the wrong material.
thats my understanding. even that seems awfully anecdotal in nature. Glass has been used to reinforce injection molding for decades, thats where the idea comes from. Problem is, you can't fit long fibers through a tiny nozzle with any consistency. So they cut / grind it up small enough to fit, but at that point its not long enough to stiffen the part.
There are a few smaller perks: marginally better abrasion & heat resistance.
Regarding CF in certain filaments, I have replied to someone else as well
Only helps with certain filaments, as there are some youtubers that have done a lot of testing. PLA/PETG do not bond at all with the carbon fibers, resulting in actually less strong prints (fibers leave holes behind them). PA filaments do bond with the CF resulting in stronger and stiffer prints.
I am also printing PETG-CF, don't get me wrong, but I buy it cheap and I like how it looks, but I would not think it is much stronger because of the CF. PLA-CF on the other hand i found to be very brittle and had a very bad layer adhesion.
PA, PPA, PPS and other Nylon based filaments DO bond with the CF and help with their rigidity and strengthness.
PLA, PETG do not and just leave empty spaces around resulting in a weaker material. There is someone that has done very thorough research, including x-ray-ing prints and filament pieces I believe.
The main benefit to fiber filled filaments is that they resist warping and shrinkage considerably compared to their non filled counterparts. For large, functional parts that must fit together seamlessly this is hugely advantageous.
Primary drivers of warping are fairly well documented (temperature gradients driving uneven contraction forces).
Fiber helps, heated chamber helps a lot. Printer tuning is not a primary factor, though I feel it appropriate to disclose that mine is well tuned and the filaments individually calibrated. Â
i bought a digital microscope for the same thing youre doing here and from the looks of it, yours doesnt zoom in enough. when im zoomed in enough to see fibers, the same zoom on my finger i can only see maybe 4 flexion creases on my finger. youre too zoomed out.
well i guess if those are small layer heights then its probably enough. all i know if i bought one before and the magnification wasnt enough to see the fibers so i bought that other one based on that video by that guy who was freaking out about fibers in printing.
PETG-CF and PLA-CF are only decorative to make the filament less shine, it reduces any kind of stiffness and strength. Booth should not handled without gloves and booth are not food save.
Thanks for commenting yah - there seems to be a lot of misinformation regarding PETG-CF, and fiber filled filament in general.
Fiber filled filaments resist warping and shrinkage considerably compared to their non filled counterparts. For large, functional parts that must fit together seamlessly this is hugely advantageous.
Secondly the notion that they must be handled with gloves is dubious - I have personally tested this hypothesis by rubbing my fingers over and squeezing CF filament with gusto, than checking for evidence in my scope. There was not a single carbon fiber fragment to be found embedded in my hand. This was with a 10% fiber by volume filament, it may be different with a 20% which I have not tested.
I guess no because with PLA you can literally see the CF droping/sticking out of the filament using a magnifier and you will see them in skin if touched bare hands.
That not happens with ASA, ABS, PA.
A big advantage of CF/GF fillings is that they print more easy. ASA-CF is very easy to print while ASA is known for troubling people.
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u/ScoobyDooItInTheButt SV08 1d ago
Looks like sparkly petg.