Carbon Fiber ABS

[uc3d]

Printer Model

Voron 2.4

Extruder Type

Clockwork 2

Cooling Type

Stealthburner

Hi,


In https://docs.vorondesign.com/materials.html it is recommended to use ABS.

Steve Builds, in one stream, confessed that one of his printers actually uses CF-ABS. It seems that it was not approved of, at the time. Is that still the case? Any reason for not using CF-ABS?


Thank you

 

[NoGuru]

CF-ABS usually looks better but performs worse as far as strength. A better material would be CF or GF Polycarbonate.

 

[uc3d]

Thank you. I will try and investigate what strength features are different. Because ASA is similar but not quite ABS, and I would expect ABS-CF to be similar, but not worse than ABS.

 

[tillin9]

CF-ABS usually looks better but performs worse as far as strength. A better material would be CF or GF Polycarbonate.

I know there is a wide variety of materials - care to explain where this generalization comes from?

I only question since it goes against my (admitted limited) experience which is the couple of CF-ABS I've used have equal or better strength with better stiffness. The expensive MatterHackers CF-ABS I used with a datasheet was basically the same as their regular ABS but double the stiffness. The cheap iSANGHU CF-ABS I used seemed to perform the same. With both, I experienced regular ABS parts that broke (usually since they needed to be too small/ delicate for the forces involved), that didn't break at all in CF-ABS. My default ABS is Hatchback.

I do definitely agree that most CF blends have the additional advantage of being nicer prints (less warping, matt texture) but at the cost of needing a hardened nozzle and costing significantly more per kg.

 

[chunky.monkey]

My experience has been similar to @tillin9, slightly stronger parts that have MUCH better surface finish than regular ABS (I don't know why, but CF-blends just seem to print really well. The only caveat not mentioned is that I they also require good venting as I imagine CF particulate isn't great for your health.

 

[NoGuru]

I know there is a wide variety of materials - care to explain where this generalization comes from?

I only question since it goes against my (admitted limited) experience which is the couple of CF-ABS I've used have equal or better strength with better stiffness. The expensive MatterHackers CF-ABS I used with a datasheet was basically the same as their regular ABS but double the stiffness. The cheap iSANGHU CF-ABS I used seemed to perform the same. With both, I experienced regular ABS parts that broke (usually since they needed to be too small/ delicate for the forces involved), that didn't break at all in CF-ABS. My default ABS is Hatchback.

I do definitely agree that most CF blends have the additional advantage of being nicer prints (less warping, matt texture) but at the cost of needing a hardened nozzle and costing significantly more per kg.

Here, this is an in-depth look at CF materials and some GF. I think I agree with almost all his findings as well as people who have been in this field for a long time.

 

[tillin9]

Here, this is an in-depth look at CF materials and some GF. I think I agree with almost all his findings as well as people who have been in this field for a long time.

Thanks.

By and large, I agree that adding CF will enhance axial strength to the possible detriment of layer adhesion. That seems to be the main item in the video as to how CF-filled filament is weaker than the standard variety, although the video really only mentions it in the PLA-CF section. I haven't used PLA-CF since, as the video suggests; it's a gimmick - PLA is already easy to print with and very rigid, so adding CF doesn't add anything (except maybe texture). I also agree that historically, most polymers used for CF blends (mainly Nylon and PC) have such high layer adhesion that it's not really an issue if the CF slightly degrades layer adhesion. The video demonstrates that a PC print in vase mode can't be pulled apart with bare hands/ simple tools.

I am not trying to be contrary, but empirically, I have seen better layer adhesion in my CF-ABS prints than in my base ABS ones. When I have broken ABS-CF parts, they don't delaminate. As I print my ABS and ABS-CF with the same profile, it's not like I'm dumping more heat in to compensate with the ABS=CF. I will cede that I don't have a good theoretical mechanism as to how this could be the case. Maybe the CF somehow enhances thermal conductivity?

Regardless - this whole discussion does make me want to test out some PC-CF and see how it compares. iSANGHU has a similar version to my goto ABS-CF on sale for a reasonable $38. I do suspect the PC-CF parts will be ultimately stronger than ABS-CF ones.

However, the video doesn't really present sufficient evidence that ABS-CF is/ should be weaker than stock ABS.

Since I asked for evidence, I will present mine. Very few manufacturers provide detailed datasheets (and comparing brands may also be challenging due to different testing methods). Still, I thought it was Matterhackers - I just purchased it from them - it's 3DXTech and does have these:

https://www.3dxtech.com/wp-content/uploads/2021/03/ABS-TDS-v03.pdf
https://www.3dxtech.com/wp-content/uploads/2021/03/ABS_CF-TDS-v03.pdf

Specifically:
Strength: 42 MPa (ABS) -> 46 MPa (ABS-CF)
Flex Modulus (bending stiffness): 2000 MPa (ABS) -> 5200 MPa (ABS-CF)

Hence, in addition to my anecdotal experiences, my basis for believing that ABS-CF is mostly the same strength as ABS but with increased stiffness.

 

[Sandman50]

If you really need a part that has high strength, then part of the design and slicing process is to orient the layers so that inter layer adhesion isn't an issue with how the part is loaded.

I mentor a high school robotics team, we use PA6-CF for the main load bearing drivetrain parts. Works well.

 

[Rat_Patrol]

I'm not sure with ASA CF, but I can get PETG CF much stronger than plain PETG simply because I get turn up the heat and turn off the parts fan. You would get the same increased layer adhesion with the same settings with regular PETG, but the stringing, sag and print issues would prevent it on most models. With the CF added, it retains shape and prints well with these hot settings. My parts printed this way don't break along layer lines.