Transcript:
This roll of Colorfabb. Xt-cf20 has been sitting untouched in my shelf for over a year now. Now I finally found the time to put this. Carbon Fiber filled material, though its paces. This week, we’ll be looking at print quality, mechanical strength and temperature performance of this more exotic material and I’’ll also talk about some safety concerns. Guten Tag everybody and welcome to CNC Kitchen. Colorfabb XT-CF20 comes nicely sealed on 750g spools that sell for 50$ which gives it a price of 67$/kg. This filament is based on Colorfabb’s XT material, which is Co-Polyester based and filled with 20% carbon fibers. The carbon is added as very short fibers, which, during the printing process orientate themselves in the print direction, which gives the parts very unique properties on which I will come later. When printing this kind of filled materials, it is very important to use abrasion resistant nozzles because otherwise, the inside of the hotend will erode away in no time I used hardened steel 04mm nozzle from E3D, which is capable of handling this task. Tungsten or Ruby nozzels are also an option but never ever print reinforced filament with a brass or stainless steel nozzle. Usually I print my whole set of test samples and then analyze them. Unfortunately, I noticed after my first run that the printed parts showed quite a lot of porosity, probably due to moisture, so I dried the roll of filament in my oven At 65°C for around 6h and reprinted all of the material test samples and this filament test ended up to be way more effort than I anticipated. The first thing I noticed was that instead of an extrusion factor of 100%, I now needed to increase it significantly to 113% to get good prints. I printed all parts as always on my Original Prusa MK2S, where I added. Some Magigoo on the 70°C bed and didn’’t have any warping or first layer adhesion problems as soon as the first layer thickness was set correctly. I tried fan speeds between 0 and 100%, where starting at 25% The overhanging parts of the prints looked very nice. In the end, I settled with 35% fan for the rest of the samples. I tried nozzle temperatures between 230°C and 270°C which all worked fine, though 250°C looked the best and had proper layer adhesion. So this was the temperature. I used for the rest of the prints. Since the material is a Co-Polyester, I had some issues with bits of material sticking to the nozzle and the heaterblock, which let loose from time to time and ended up on my parts Overhangs printed great up to 65° and boy, look at these outer surfaces. The Matt look gives the parts a finish. I haven’’t seen so far with any other material. The material doesn’’t string but left some nasty material blobs at the stringing test, though fine details came out well. Playing around with retraction settings and using dried material would probably increase the quality. Bridging was strange because at first, this part looked really awful. Out of curiosity, I used Slicer Prusa Edition instead of Simplify3D, which made such a difference. Almost perfect bridging even at the largest gap, I tried to tune the settings in Simplify3D, but nothing I did improved the quality, which is really strange. The 3D benchy reflects these results because it showed the blobs at the retraction points and some material bits at a couple of places Still. If you overlook these, then the rest of the boat looks stunning with the Matt Black finish. Let’s now take a look at the material properties of Colorfabb XT-CF20. The tensile strength of around 45 MPA before drying it wasn’t very impressive and even lower than regular unfilled PETG. After drying the material, it improved more than 20% and ended up 55 MPA, which is better but still below regular PLA Layer adhesion was only okay, and the specimens printed standing failed at 18 MPA, which is only 1/3 of the strength of the lying specimens. The tensile modulu’s. So the stiffness of this material is what really stands out because with almost 3000 MPA it is the most rigid material I printed so far. But here comes the interesting part. This was the first time when I also tested the stiffness perpendicular to the printing direction. So with the upright specimens. If we take a look at a microscope shot of the material, we see that the carbon fibers orientate themselves in the printing direction and these fibers give the material. It’s superb rigidity. Perpendicular to the printing direction, they are only barely adding strength and stiffness, which is verified by my second test that showed a tensile modulus of only 1100 MPA in this direction. So keep this in mind with your designs. If you use fiber reinforced materials, they have very different properties in and perpendicular to the printing direction. The filament test also confirmed the superior stiffness of this material even in comparison to PLA. The slope at the beginning of the test indicates the modulus. The steeper it is the more rigid a material is. My test hooks failed at around 50 kg of load, which is in the midrange. The standing ones only were able to bear 16 kg until failure, which confirms the previous tests. Temperature resistance was good, and the material stayed rigid up to 80°C and then totally failed at 85°C. The impact strength was okay and an improvement over regular PETG or PLA, but far away from the toughness of for example, Polycarbonate. I’ve been mentioning safety concerns in the beginning. This material is filled with lots of very tiny fibers, which might come loose during printing, cleaning or reworking. I wasn’’t really feeling comfortable printing the XT-CF20 in my office and when reworking this material, which, by the way works very well, a respirator is a definite must. I don’’t know, I’’m overcautious, but I have a bad feeling having these particles in my office. What do you guys think? All in all, it was very interesting for me to work with Colorfabbs XT-CF20. It requires some setup. Due to the special nozzles needed but delivers stunning looking parts. Overall strength was only okay, but the stiffness of this material is really standing out. If you need a material that is stiffer than most other materials, this is definitely not a bad choice. If you require only strength and toughness, there are other materials around. That might be more suitable. You can find links to the material and the test methods. I use down in the description. The detailed test report together with print profile and all test sample are available for my Patreon’s. If you enjoyed this video and learned something, then hit the like button and subscribe to the channel for more. If you have suggestions and comments about my methods, please leave them down below and let me know what other material you would like to see me investigate in the future. Until then, thanks for watching auf wiedersehen. And until next time.