Lazy annealing of PLA (covered on heated bed after 3D printing)
ฝัง
- เผยแพร่เมื่อ 19 พ.ค. 2024
- Annealing of the PLA will improve properties of the printed object, mostly temperature resistance, but the object will deform during this method. Using the oven is not too accurate method and uses too much energy. Heating covered on 3D printing bed is simpler solution and saves energy too. But is it worth it? Let’s find out..
Results you can download from:
www.mytechfun.com/video/304
In this test I used Amazon Basic PLA and everything was printed on Ender-3 S1 Pro.
Contents:
0:00 About PLA annealing
1:15 Test objects
1:35 Reference PLA
2:00 Annealed PLA
3:48 Shrinking
4:42 Pulling test
5:12 Layer adhesion test
5:46 Hook test
6:13 Bending test
6:59 Impact test
7:41 Temperature test
9:03 Creep test
10:03 Results
12:29 Conclusions
#3dprinting #annealing #pla - วิทยาศาสตร์และเทคโนโลยี
I´m annealing a lot of PLA with the "lazy method", but 100 degrees straight from the start is too high as the PLA will get very soft initially. What works best for me is to heat up the bed to 80 degrees for one hour. The parts will shrink minimally and will not warp at all. If I want no dimensional change at all, I use volcano PLA. After that treatment the parts are heat resistant enough to withstand boiling water without any deformation . If I had a very delicate part with overhangs, I would heat the bed to only 70 degrees for around half an hour and then proceed with 80 degrees for another hour. Why? - if you start with a lower temperature just above the glass transition temperature the parts will gain some temperature resistance without getting too soft. The "partly annealed" part will then be temperature resistant enough to go for a higher temperature and so on.... About the annealing in water (I tried that too) I can say that it works , but you will need a very tightly controlled heater and thermometer and keep the water at the same 80-85 degrees in the beginning. Putting the part in 100 degrees water will cause the part to warp immediatly, so thats not an option. There is one more thing to consider (I´ve tested this with thin walled PLA test parts printed from different brands PLA and PLA+): Some of the PLA variants that are fine when annealed with the 80 degrees dry method will get super brittle when annealed in water. I don´t know why that is, but my guess would be that some filaments react badly to hydrolysis ??? (any chemists around here ;) )
@@polycrystallinecandy the pieces I anneal are usually little tubes with a slit on one side, diameter and height are around 30mm, wall thickness around 1.5mm. So I can´t say much about parts with infill. What is important though is not to anneal the parts for too long. If you just let the parts sit on your printer bed for too many hours, it will warp even if you annealed with a lower temperature. So I guess the sweetspot is were you get the heat resistance you need with the lowest impact concerning shrinkage and warping.
One more thing that I forgot to mention, I did all the annealing with the original ender 5 pro build surface. Its these flexible sheets with (I guess) a polycarbonate layer on top. PLA sticks very well to this, so even after the annealing parts are still stuck to this, they won´t self release. That might also be a big factor why this works so well for me.
this should be his next video, what small temperature increase to final temp is the best.
There is a g-code for that... Quite easy to program an annealing process. It could be that going in steps, 50C, cool down, 60C cool down and so on would preserve dimensional accuracy the best.
Also, the slower the plastic cools down while printing improves heat resistance. That is when the plastic becomes amorphous in the first place, when it is cooled down in a second, freezing all polymers in place. Once it is heated, it changes semicrystalline, the polymers can organize and pack themselves more efficient..
So, it makes sense that doing it in steps, or just very slow heating would work better.
There is very simply explanation for PLA annealed in water, i just wrote a comment about it, so i'll copypaste:
"PLA, heat and water do not mix. It starts to hydrolyze and becomes brittle. The polymers get shorter. So, annealing in boiling water is not recommended. Humidity should be kept away when annealing, the closer to zero the better."
Poly-Lactic Acid is made from glucose that is converted to lactic acid. Then we remove basically one H2O from it, that forms monomers. Then we apply heat in ABSENCE of water to snap those monomers end to end, to form polymers. So, PLA really wants that H2O back. Apply heat to decrease energy needed for a reaction to happen, give it water sources and... it will hydrolyze.
Annealing with print bed is great idea. i use this method to dry my filament. Heck! I even cook sous vide steak with my print bed 😁
Nice! Ive used my hotbed to unglue my broken tablet screen also to dry out a phone which fell in a puddle(after washing it with distilled water)
@@Mwwwwwwwwe surprised it still works next time use 90 percent or better rubbing alcohol on your phone to rinse it takes water out as well that's how they fix keyboard that have been spilled on is my soaking in rubbing alcohol
@mikealnutt360 distilled water is non conductive-(doesn't have any disolved mineral salts ) to short out electrics also non corrosive. I've had Isopropyl ruin lcds before
Anecdotally, i have annealed in a sous vide circulator with the part in a plastic bag and also in a jar packed with salt. The plastic bag only had deflection in thin walls and dimensional changes. The salt had no deflection in thin walls but still dimensuonal changes.
That was really interesting, Igor. Thanks.
Testing the annealing temps in 10 deg increments would be informative.
It would be great if the hot water reduces the warping. Looking forward to that video.
Beautifully tested. I learned some good information from this. Thank you!
Another great set of tests, thanks very much for your continued careful, meticulous work!
(Never heard of boiling water before, I’d be interested in learning about it.)
Thank you for trying out "lazy annealing"! Your tests are quite impressive! I use it for increased heat resistance,and so far I'm satisfied. I haven't tried boiling water. There are also many good ideas in this comment section, which I'm curious to try out. As I mentioned previously, I think that many of us are curious about remelting in fine grains, and a comparison to the "transparent fdm settings" featured in a cnc kitchen video from 10 months ago. But it is definitely a lot of work to test it out.
Very thorough -- thanks for this!
I love your comprehensive testing! I think the biggest use case (like you said in the video) would definitely be temperature resistance
sous vide annealing sounds delicious
I like videos like this. Good job!
Interesting as always.
Regarding deformation and warping, have you done any experiments (would like a link if you have) on warping and/or stress deformation with different infill patterns?
Thanks for another great experiment.
Very interesting and a nice video. I regularly anneal pla to improve temperature performance. I use a water bath 75C and near 90% infill parts. Put hot water in a pot, add cold water to bring down to temperatures, put parts in, cover, come back in an hour. I have had good results with fiberlogy impact pla. Only get 1% shrinkage and heat resistant >110C. The buoyancy of the parts in the water help prevent warping.
I just started the water test, 95C but this looks too much, object still deforms.
I postulate that annealing process will, to some extent, remelt the layer welds, and they may re-weld inconsistently, giving unpredictable mechanical strength results to the parts. I like the staged annealing idea. That should mitigate some of the unpredictability.
I think focusing more on slicers to create holes in T shapes in walls/infill then inject filament after few layers. This could create interlocking patterns and end up very strong
Annealing Nylon in boiling water is something that people do in the combat robotics community because it not only anneals the part but rehydrates with the theory being that it increases the impact resistance of the part. I don't know about other filaments but I would definitely be curious to see testing of PLA, ABS, PETG, Nylon, PC, and maybe even TPU? though I know that TPU doesn't work well with your typical testing methods.
PLA can't be boiled, it will hydrolyze and become brittle. Any application of heat should be done in low humidity environment.
I don't know about water annealing but I've heard good things about salt annealing. However the salt annealing adds a texture to the part. Maybe with a finer medium it would work better.
Great video. Keep up the good work.
The salt approach isn't (just) annealing but remelting to get isotropic part. Depending on how it cools, it may or may not anneal afterwards.
I wonder if the warping is due to the inconsistent heating from the print bed, from the bottom up, perhaps water would work better, heating evenly.
Or is the warping from the cool down process because the air would cool faster than the bed? Next time, try a clear glass bowl. ;)
PLA, heat and water do not mix. It starts to hydrolyze and becomes brittle. The polymers get shorter. So, annealing in boiling water is not recommended. Humidity should be kept away when annealing, the closer to zero the better.
Salt annealing works well. Also, i have tested casting PLA, which is not easy as it is so viscous, but the results were amazing. Temperature resistance comes as a side-effect, and i learned that annealed, uniform PLA is extremely hard and tough material. My mind was blown. I made a mold from wood, since we are "casting" at relatively low temps, sprayed temperature resistant paint as mold release (worked amazingly well, it adheres to the plastic permanently with very nice coat quality), melted some scrap PLA with a heat gun, popped in the oven for an hour, took it out, closed the mold which pushes plastic to really fill the mold, and let it cool down on its own. The "technique" requires two sided molds, like injection molding, you just insert the plastic yourself and give a lot of room for flashing. My models had a flat bottom, which meant my upper mold was just flat piece of metal, clamped to the wooden mold.
I've done similar while restraining the movement of the part in some manner. Minimizes the dimensional changes while providing the benefits of annealing.
EDIT: Can't say I've heard of PLA being annealed that way, but I've seen it done with nylon. A variation that worked really well was to anneal in an oil. The oil kept the humidity out during the annealing process and provided a surface treatment that prevented future adsorption.
The thought of annealing in boiling water makes me wonder if it would be worth trying it under pressure. The 'Instant Pot' and clones are readily available and relatively inexpensive.
Yes, to prevent air pockets/hollow infill from warping the part with unequal pressure you want slow heating/cooling in a sealed chamber.
Not sure what the theory behind the boiling water sous vide method is. It does not provide support really to prevent warping or deformation. Compared to the lazy method the heating would be more uniform, because here with your test the heat conductivity difference was big. I think the main reason that the impact specimen warped is that one side was touching a high thermal conductivity print surface, while the top side was warmed by the trapped air only and without airflow. Parts suspended in the middle of an oven get more uniform heating. To prevent deformation while annealing there are two known solutions. One is to burry the prints in a fine powder material that does not melt or react with the plastic, like sand or salt. The other is to use filled materials. Carbon fiber, glass fiber or mineral filled materials will deform less during annealing. This is because the main cause of the deformation is that there are stresses that build up between the polymer chains during the printing process and heating up the material and softening it, helps release those stresses. That is why on the Z the parts expand, it is stress release. Carbon fiber nylons can be annealed and PET CF can also be annealed like the new PET CF from UltiMaker, PET CF from Luvocom, PET CF from Phaetus, Raise3D, BambuLab and QIDI. Pay attention that only PET materials without the glycol modification can be annealed. PETG and PETG CF can't be annealed effectively because glycol reduces the crystalinity of the material.
Have you tried annealing inside a plaster of paris mold? I have heard of using salt and sand but these are not dimensionally accurate. Thought making a plaster of paris mold or sleeve might solve this... By the way, I love your work!
There is a plausible mechanism for annealing to make layer adhesion weaker: if the layer adhesion is partly relying on mechanical interlocking of texture like a hot glue gun would do, rather than actually welding the polymer. I find this is what happens when printing at recommended temperatures like 200-220 rather than 260+. In this case, warping would reduce layer adhesion the same way cooling breakd bed adhesion.
Sounds like a good ‘reason’ to buy a sous vide circulator 😊
Is it worth making a negative mould that you place over the model to control the warping while it annealing. Obviously a mould or form would have to be higher transition temp than part to avoid warping.m itself.
It would be interesting see how eiger (mark forged) scales the part to account for warping, ie if z is 1.05 larger then they make it at scale 0.952 so final part is 1.0 and like wise length wise and width too. So the “green” print would be a really warped shape vs final sintered/ anealled part.
Cadmould is a software that has modules to compensate for warping. It’s all Price on asking so won’t be cheap…
I would think this comes down to the cost benefit analysis for each part. If you’re doing this professionally, build the cost into the price, but you’d better be getting guaranteeable results.
My friend did the boiling method with ABS and it increase the melting temp a little. But i never tried it myself.
You could also try annealing inside tightly packed, fine-grained sand.
Or fine milled salt ;)
I would love to see a water annealing test, as far as I know it should minimize warping.
PLA becomes brittle when cooked.
What if print pla completely enclosed in pva then lazy anneal it and then dissolve the pva, will it hold the shape?
You should probably try with a bed surface that maintains adhesion under changes in temperature rather than these things designed to release with thermal contraction.
What about annealing in packed salt ? It requires 100% infill but I have seen great results online l. Never tested it myself.
we did not but you can :D
- water
- sand
- fine sand / powder (gypsum for e.g.)
What was the last material survived the heat test?
Sunlu Resin from my previous video.
@@MyTechFun I will check it out. Thanks bro
Can you "pre-anneal" pla by printing at an ultra low temp in a heated chamber?
Lol..funny idea...but 100° is probably too much....I would go 70° max😉
more on annealing in water: th-cam.com/video/Rc85APSK9vo/w-d-xo.html