Filament snapping in feeder S5 Carbon Fiber Nylon BASF PAHT CF15

[Projects 2]

The material is new, the feeder is not too tight from what I can tell. It did fine for the first half of the roll, but it seems now that the material is snapping when the feeder forces it more strait because the material on the spool has a smaller radius as the spool gets lower and lower? I keep my spools in a sub 15% humidity room, but the room is also my print room and so it gets hot, between 95 and 100F normally. I dont generally have a spool for more than a month. The BASF PAHT CF15 that is giving me issues I have had for less than 2 weeks. again, it did about half the roll with no issues. I have tried to put the roll in my material dryer for 24hrs and no change I can notice, so I don't think it is moisture. 

I got a brand new roll in yesterday, just to be sure it responds the same...I expect it will do fine the first half then start breaking also?

Any ideas?

[geert_2 558]

 

In PLA-based filament it is known that microcracks can grow if the filament is bent or stretched (thus kept under a load) for a longer period of time. So, don't let material sit still in the feeding-traject after the print is finished, but unload the spool immediately.

 

Some materials also get brittle due to changes in crystal structure, becoming more crystaline (often reversible), and due to moisture absorption and damage (not reversible as far as I know). Both happen in PLA.

 

Keeping it dry obviously helps against hydrolysis. But I am not sure what the best solution is for "un-crystalisation"? Melting should help, but then you lose your filament. Heating up to the point just before deformation might change its molecule structure in both ways: making it soft again, or rather making it harder (encouraging crystal growth), similar to post-curing and annealing. I don't know which one wins. And your warm room might speed-up these effects?

 

I don't know your material, so I have no idea if it is affected by these phenomena.

 

Try what the effect is of heat on a few short pieces of this filament.

 

Keep in mind that when heating it too much above its glass transition temperature, it will shrink in length, but get thicker (e.g. from 2.85mm to 3.10mm), and then it may no longer fit in the bowden tube or nozzle. You could also try unwinding it manually, and manually straightening it a bit, after which you release it again (to stop crack growth), so the bending radius is not as tight as before. Then it will get stressed less in the feeder. It may take trial and error.

 

It could also be a bad batch or spool, or a filament that is very brittle by nature, especially if it is a filled filament.

 

Pictures:
Microcracks in PLA/PHA filament after straightening it, and then releasing it again, so the stress is off. If the bending stress would be kept on, these cracks would keep growing until the filament would break.

 

 

[Projects 2]

Any other thoughts? For now I am going to try and re spool the material into a much larger spool so that the radius is larger. this stuff is so so stiff and brittle. I tried heating it up to 200f and it was able to bend to about 5 degrees before snapping. Its almost like it needs an inline heater to bring it up to 250f before it goes into the feeders (both the feeder behind the machine on an S5, and the hot end.)

[Kaechele 0]

Did you have any success with respooling it or did you get it to print reliably in any other way?

We are experiencing the very same problems with this PAHT CF15.

 

Regarding comparisons to other filaments, I understand PA-based filaments are very hydroscopic (far more so than PLA), but everybody and their uncle kept saying that about PVA as well, and drying it again and again and keeping it in the Material Station only increased its brittleness for us. In the end the successful solution was to keep our PVA in the open for several days, and by absorbing just a bit of moisture from the air, it became smooth as silk and printable again. I'll just leave that as a side note here.

 

Now to get back to this stuff here, BASF's TDS for PAHT CF15 states:

Quote

 

Drying recommendations to ensure printability: 70 °C (158 F) in a hot air dryer for 4 to 16 hours

Optimum drying recommendations for best mechanical part properties: 80 °C (176 F) in a vacuum oven for at least 40 hours

 

 

Looking at it that way, it should not be possible to over-dry this in any way, it's the dryer the better full stop.

Your 200 F (93°C) may have been a bit too hot, for how long did you condition it this way?

 

Unfortunately, I have not yet had the possibility to try these recommendations, but I'm very interested in your experiences.

 

 

[Projects 2]

so, I actually contacted BASF about this issue. They said that they get complaints all the time about the 2.8xmm CF15....and what was shocking is that they had no solution, in fact they said to let them know if I found one? lol, whatever. not here for what I think about that 😄

I honestly think it has a lot more to do with the composition of how they are making the PAHT. Its highly modified Nylon, higher temp resistance and far less subject to moisture, but this makes it super stiff stuff. Like, right now we are getting crazy performance from it. we put it in a soap mixing/making application with up to 400in/lbs of force on less than 100sq/mm of surface (a shaft key). What is far more crazy is that it is in a steam saturated and near 200f environment + essential oils/vegi oils...all crap that can really wreck plastics. The chemicals we use literally melts PVC into mush in hours. AND that is the conditions for hours at a time multiple segments per day 5 days a week. All to say, this stuff may be the most tough plastic I have seen that can be printed on an ultimaker/like machine.

What I ended up doing is converting one of the UM5 printers so it can do 1.75mm because the PAHT CF15 that is 1.75mm has absolutely no issues according to BASF, and that has proven true. Just know you have to change some CURA settings to get it to work. you also will need to make a few modifications to the feeder and tubes. For me, well worth. I wish really high end printers were out there (ultimaker quality + build volume at a reasonable price) that could do 1.75mm out of the box.

[Kaechele 0]

Wow, this is interesting information, thank you.

 

I'm afraid a 1.75 conversion is out of the question for us, I won't modify our brand new and only S5 just to print this stuff. Your application is certainly special, and I'm impressed by this PAHT's performance under those circumstances. It is a great material, and when it does, it prints absolutely beautifully as well, I admit that.

 

But I also have some thoughts I better not express here about them putting the 2.85 version to the market when it explodes in your face all the time. It's not like nobody could have noticed it before. The answer they gave you is... disappointing, to say the least, and I find it hard to swallow.

 

In the face of this, what I will do is publicly advise anybody to not buy this material unless they really, really see no alternative and are willing to cope with the most dastardly stiff and brittle (to the point that it acts like it was literally made out of glass) filament they ever fed any printer, leading to a lot of failed prints and even more unnerving cleaning of the machine. We mostly needed several attempts (read: insert, try to feed, have it break, open bowden, sometimes even open the feeder too, clean out fragments, close, pray, repeat) to even have it reach the print head. Now we have two spools sitting on the shelf, and I don't know what to do with them, because I really want to spare myself the hassle of dealing with any more of this; it's a waste of time and money.

 

Another thing we noticed (at the times we got it to print, that is) is some very heavy shrinkage in z-direction that makes it kind of hard to predict the dimensional outcome. Do you experience the same? How do you cope with that?

 

You have not by any chance ever tried the LUVOCOM 3F PAHT CF 9742 BK? It looks very similar if not superior on paper, and it even has the "Optimized for Material Station" label, so I would guess it should be a bit more tame...

[Projects 2]

Yeah, not super happy about the response from BASF...to put it lightly.

 

fair to the advice. I would say the same. If I can find a = or better material out there for this use case, I would switch. Fingers crossed, because I do like keeping the printer on its native material thickness.

 

I have not heard of the LUVOCOM stuff. Please let me know where you get it from and how it works! Impressive that they say it works for material station, I didn't think any chopped materials worked in the material station. I have another U5 with material station doing all our "regular work". Im honestly not super happy with the thing. It still seems like I have moisture issues, even in an enclosed room with a dehumidifier sub 10% humidity on the meter in the room...materials in the station still pop at times. It could be that I never actually dry any of my material because it always stays in that room after opened.

 

looking at z measurements from design to final parts....I honestly don't have accurate enough measuring methods to do a good job at z. It seems like I am getting a little shrinking using just a digital caliper between two printed surfaces of the same part. (I am not sure if I could use bed to printed surface as a real proof, because that first layer I could see being slightly thinner than designed. measuring for me is most often fit related, and in that respect I feel like I have actually had less contraction than other exotic materials like CPE+ (that stuff is tough, but print quality is nasty). ANYWAY it seems like I could be getting anywhere between .2mm to .5mm z-direction shrinkage. but again, I really don't trust my measuring methods on this.