As a continuation to my testing with printing PA… I have done some large prints with PA-CF and got “extruder overload” after a few hours. I was printing with 0.4mm nozzle…
reducing the flow rate from 8 to 6 solver the overload issues.
Also it seems that with small parts and lots of head moves it was OK even for a 10h printing.
Further more as I straggled with support I found that using ASA for support interface give wonderful results. The PA sticks to the ASA during printing and separated very easy when needed !!!
I have a new issue. Attached is an image for the last part I have printed. It looks great, almost like SLS but the layer adhesion is not so good. Its OK but so good
I have triad adding a modifier at the marked areas with 100% infill but that did not help as well, broke when applied force. It was printed as shown.
If I anneal or raise temperature while printing will it help getting better layer adhesion ?.. the printing profile was Bambu PA-CF default.
What about sealing/dipping the part with a substance like Dichtol ?
This part used an ASA interface for supports? And those are the layers with weak adhesion?
If you had not posted in the H2 section, I would have assumed a purge volume issue, but you are probably printing from different nozzles anyway…
But do not expect miracles. Z-layer adhesion is an obvious FDM bane. From the Bambu datasheets for non-flex filaments, only PA6-CF gives a z-impact resistance higher than PLA Basic: By barely 12%…
From a CAM point of view, you could strengthen the handle if you printed it lying on its side. This would give you a continuous outer wall in the weak area. But of course this would increase the need for support drastically…
ASA from the AMS and the PA from the external spool (from Polydrier).
The week adhesion is were I marked. Yes I am aware that Z layers is a weakness of FDM.
The round rod is not a handle but rather a cable guide.
This part is placed over a tube and two screws hold it in place. I am planing to talk with the designer to maybe change the design. To have a thicker guide and maybe put the screws at the guide ends… This way it will hold it in place and strengthen it.
I wonder if anyone has had experience with annealing PA or used Dichtol and got better Z layers strength ?
I am afraid that my experiences with crystallinity in composites are not related to FDM. From my theoretical considerations though, I would expect in particular in-plane property improvements. Out-of plane-property imptovements will occur, but not as prominently as in-plane properties.
Thanks for the Dichtol hint. That looks quite interesting. Unfortunately, I could not find further information than “single component system”, so it is highly questionable if there would be any meaningful bond strength achieved between PA6 and Dichtol. It may be best to directly ask the manufacturer about compatibility. Marketed as an FDM specific product, they should really be able to give performance data at least for common materials.
This will always be a weak spot of this model.
You could reinforce this section by adding a pin that you glue in or a screw from the back. I do it sometimes if I need extra strength.
The part is held in place with two screws. I already talked with the designer to strengthen the breaking ping significantly and also move the screws to the center of the angle of the “handle” this way it will be much stronger.
For now they sent it to a constructor to print it from SLS … will see.
According to my favorite Hungarian mechanical engineering PHD MyTechFun, PA6-CF doesn’t have great layer adhesion. Something like PPA-CF might work better. Interestingly, none of the Bambu filaments (PA6-CF or PPA-CF) had good layer adhesion for their class. I like Siraya Tech PPA-CF, which has about twice the layer adhesion of PA6-CF (and prints nice), but Creality and Qidi PPA-CF tested even better.
If you were running into extrusion issues at 8mm3/sec then you are likely not printing hot enough. You want it as hot as possible, Run a temp tower, then a flow rate test and print at like 50% the flow rate that you got your first signs of issues on the flow rate.
By running into extrusion overload issues that means you were likely barely into the proper temp, and cool extrusion temps make layer adhesion much worse than normal. I would also throw in a 0.6 nozzle if you have one before calibration, to let it flow a little better and more consistent. It has been proven in the past that the fatter the extrusion line and layer height, the better the strength and adhesion.
I have printed some tests today with Sunlu PA-GF. As I do not have a profile for it I chose Bambu own profile as a starting point.
From previous experience I used ASA as support interface but it was almost impossible to remove. Second attempt was with HIPS as interface.It was also not easy to remove but after removing the surface was clean.
To my surprise the adhesion to the plate (BIQU Glacier) is very strong and also part seems very strong.
Considering the price per Kg of this filament it is simply wonderful.
I also ordered a few Kg of ESUN PA-CF, lets see it behaves…
I’ve never seen the allure of PPS-CF. It’s super expensive and requires a very hot hotend, but it seems to be inferior to the simply expensive PPA in most ways but the ringing sound. Do you know of its main use case?
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