I’ve been doing some prints with Bambu PA6-GF that I received free from the black friday promotion.
I’m having a problem with warping, but the print 100% sticks to the plate (engineering plate with glue). Thinking that the issue was that the print itself was lifting the plate off the magnetic bed, I installed small corner clips at 5 points around the plate to hold it down. However, that still did not fix the warping. The print was still fully adhered to the plate and the plate was still on the magnetic plate because of the clips, but when I pulled it off the plate the warping still occurred. (see attached). This is a rather demanding print (long and somewhat thin.
The only thing I can think to do is to very slowly cool the plate and chamber down after the print ends. I’m thinking perhaps the warping occurs as cooldown happens.
Yeah I read through that of course. The only thing I didn’t consider was the annealing process. But I’m not sure that would help because even Bambu states that a risk of annealing is warping.
I have had great success with the PA6-CF due to the much better heat dissipation when compared to GF. For those prints, I managed to keep my chamber temp at 60-62°C. Can’t say how though as my extremely simple way was not something anyone can consider safe
Once you have a really warm and thermally soaked chamber, you could also try with a further reduced layer height as it also helps against warping.
Annealing is indeed not going to help here as it happens post-printing. Some geometric adjustment can be possible through creep forming, but you’d need a mould… in which case you’d already be at injection moulding rather than FDM.
Finally, I assume all fans are off for this print?
After this free roll I received from Bambu, I have already decided to try the PA6-CF instead for the reasons you describe.
The warmest I can get my chamber is about 46C, and yes, all the fans are off.
I’ll try reducing the layer height from 0.2 to .15 and see if that helps.
The good thing about the parts I’m printing is that as long as the middle 2/3 is straight I can still use them for the intended use.
This is the first nylon filament I have ever tried and I’m very impressed with how strong it is. Even the 3mm wide thinner section on the ends is very strong and I can’t break it off by hand, which I would pretty easily be able to do with PETG.
I think the 46°C is your main problem. I have my X1 sitting in my office. I also like to wear cardies. When doing PA6-CF, I can usually go outsides for a smoke with a very well pre-warmed cardie
Don’t tell anyone though!!! It really can not be considered a safe way to increase chamber temps to 60°C (and I now also have a Plus 4).
I guess I don’t really understand what’s happening and when the warping is occurring. The part sticks to the plate and the plate stays on the bed. Everything is flat when the print finishes, at least as far as I can tell. So I’m going to try gradually reducing the bed/chamber temp when the print finishes.
I dare guess that the plate is still being lifted off the build plate. With the edges clamped down, the build plate may form a slight “M”.
The needed freedom of plate movement could result from minor XY sliding of the plate under the clamps. I doubt that it would be visible before removing the build plate from the printer but it may be possible to feel the shape of the post-print build plate once (gently) cooled.
In general, warping happens as a result of the cooling from nozzle temp down to the ambient build chamber temp. A hot layer is deposited on top of a near chamber temp layer. It then cools and therefore shrinks. This in turn causes a bending moment, visible as warping.
So it usually happens as each layer is cooling rather than the final cool down.
Annealing is (rarely) done after printing to improve mech properties by crystalization of the polymer. The rapid cooling during printing does not give the material time to crystalize. So that is occasionally done afterwards. However, there is an additional shrinkage associated with the crystallization which is why further warping from annealing needs to be factored in. I dare say that the neccessary prediction of this warping for adequate control is beyond the scope of most but the most ambitious hobbyists. I am sure there are some though.
I was just going to write that I now do think I see a slight “bubbling” of the plate on the ends of the part. It’s hard to tell for sure but I think so.
So how does anyone get their chamber to 62C? Insulation of some sort?
I myself found it sufficient to just put a dense cardigan over the printer (without blocking the rear though). I was always with the printer when I did that though. For safeties sake.
Nowadays, I have a Plus 4 with its heated chamber. Even prints PPS-CF very nicely. But PA6-CF still has better layer adhesion and is a lot cheaper.
