Both PLA-cf and PETG-cf have bundle sale going on. I am thinking of getting some.
Question on PLA-cf:
Does anyone have experience using it? I am interested in the strength comparison with regular PLA.The store web page only shows the comparision between PLA matte and PLA-cf.
Question on PETG-cf:
The web page of PETG-cf shows good improvements over traditional PETG in terms of numbers. Do these numbers translate into real improvements?
I’ve used mostly PLA-CF but not Bambu’s because it’s too expensive. PLA-CF and PETG-CF are among the most forgiving filaments I’ve ever worked with. You can’t go wrong with them. They seem to anticipate calibration perfectly. For example, when I ran a temperature tower, it was flawless at every setting. When I calibrated pressure advance and flow rate, the margin for error was so large that you could barely see any difference between values. Simply put, it worked right out of the box.
If I could justify the expense and if it came in more colors and a smooth version, I’d use it 90% of the time.
That said, I’m speaking strictly about appearance, strength, and ease of use. If you haven’t tried it before, note that it’s very coarse and highly matte in texture. For some applications, it might not be suitable.
If you go onto amazon and enter “filament sample 1.75mm carbon fiber”. You’ll get loads of filaments to try out. There are also about a dozen 1kg spools for under $25 with free shipping if your prime and free returns. I may have mentioned that I return about 1 in 10 filament spools if I am not happy with some even having used over 200g in an attempt to calibrate. I’ve been doing it for two years now and never got any pushback whatsoever, so there is no risk if you’re a Prime member and I generally get it either same day, or within two days.
https://www.amazon.com/s?k=filament+sample+1.75mm+carbon+fiber
Here’s one I tried last week for a high temp application where I need heat resistance and dimensional accuracy. It was $6 for a 50g sample.
https://www.amazon.com/dp/B0DSVMTCSZ/
This one has become my go-to everyday for tough precision parts.
https://www.amazon.com/dp/B08MTRCWHS/
Please be aware, that in general, CF-filled filaments for FDM have the fibres chopped in very short pieces. Those pieces easily get detached from the surface of a print and get stuck in the skin of your hands. I have seen 3 different tests, that showed the same result.
I have no idea, what happens with those pieces. The testers also couldn’t say. Maybe they just fall of, maybe they migrate into your body. That uncertainty for me is sufficient to mostly avoid them and only use them when the application makes it really necessary. This might change when somebody shows that they are harmless.
On the physical properties:
Mostly those carbon fibers increase stiffness and reduce shrinking which in turn reduces warping. That is why usually soft materials like PA get much easier to print with CF. In addition, many materials have an increased temperature resistance with CF.
At the same time, impact strength and layer adhesion is reduced by the fibers. As far as I know only long fibers really can increase the strength in the XY plane.
If by strength you mean stiffness, then yes, it improves with CF. If strength is the force that you need to break something, then most filaments actually are weaker with CF.
Regarding PLA-CF: I think the benefits are purely cosmetic ones: You get a very very matte and quite rough surface that conceives layer lines almost completely. I think it has a very appealing and high quality appearance. As PLA is already very easy to print, I didn’t see much difference in ease of printing. I get along very well with all PLA basic, matte and CF at default settings. Temperature resistance is not improved as far as I remember.
I’m not surprised that Bambu compares it to PLA matte. That probably is the closest alternative. I have measured layer adhesion of basic and matte PLA from Bambu. Matte did break at ~ 1/3 the force needed for basic. I guess that PLA-CF is somewhere in between. Since the findings I wrote above, I got rid of all my rolls although I really liked the surface a lot.
I have one roll of PETG-CF that I still haven’t opened since buying it, so I can’t give first hand experience. I think you can expect reduced warping especially on an open printer as well as much stiffer parts than regular petg. I could imagine that temperature resistance is improved. But you should find those information in the data sheets.
by strength, I meant all of them: tensile, impact, flexural, compressive, and tear.
But what Bambu Lab puts on their mechanical property comparison table are good. I made a request yesterday for a table that includes all types/subtypes of Bambu Lab filaments, linked below. I think it will be very helpful.
Thanks for sharing the experience.
I’m pretty sure only GF filled filaments get stuck in your hands
How much harder is CF on the printer components? I assume things like PTFE tubes and nozzles wear out faster. Also, if using AMS, the funnels are another item that might wear out quicker. The concern over this is why I have not printed much in CF.
Pretty much everything that comes in contact wears out faster - tubes, nozzles, filament guides, feed gears, etc. It’s one of the reasons there are hardened nozzles and feed gears.
The glow filaments are also abrasive. Probably some others I’m not thinking of right now.
I don’t remember seeing anything quantitative but quite a few have mentioned wear here.
The investigations I have watched all were about CF fibres. In the close-ups you could clearly see the black fibres stuck into the skin.
If you have the newer AMS 2 Pro, the ceramic feeder protection is tough enough, no need to worry really. Especially for PLA-CF that are typically only 5%~10% in content.
I do cold pulls for the nozzle every 2-3 rolls, residues are definitely more significant, but that’s it. (H2 Series) black dusts will slowly accumulate in the toolhead filament path, contaminating other prints, so periodically clean it out. I’ve not seen significant PTFE wears warranting replacement either even after dozens of rolls.
Heavy duty printing of PLA-CF will wreck A series AMS-lite tho, ask me how I knew 
Thanks for the reply. I will start printing CF once I get my eddy sensor issue resolved. I have a roll of PLA-CF and a roll of PETG-CF ready to print.