I know there are several topics about this - but I would love to hear from more people who have taken time to investigate warping and how to mitigate it.
From what I’ve seen, warping can be dependent several things:
- Whether curing is done with supports or without
- How long the parts have washed and dried for
- Geometry of part and print orientation
I’ve done tests with and without supports, with lower temperature, with no heat, with no heat then a standard heat + UV cure…but find that there are still some situations where warping is inevitable after curing if one is to use the default Form Cure settings.
I also know that mechanical properties are tightly coupled to a heat + UV cure, whereas a UV only cure will result in lesser mechanical properties (but still better than the green state).
In order to avoid warping, I sometimes will just cure without heat for at least 3X the time. I’ve found that this definitely eliminates warping, but I am sure mechanical properties are impacted.
One thing I haven’t tested a lot is the amount of dry time and wash time and how those affect the amount of warping one sees. Curious if anyone has some test results or knowledge from that.
Also am curious if the Form Cure L does anything differently to mitigate warping during this step.
Tried it all and nothing helped.
Regarding the Cure L it definitely way better in terms of getting the best mechanical properties (for example Rigid resin parts stay actually rigid and not “almost rigid” as they do in the regular Cure) but I have see. Only a small improvement in terms of warping and only in the area that sits in the glass (since it’s a better surface than the Cure’s holed one).
In the end I still have to bend large flat areas by hand and / or other methods and wait for it to cool off and pray I got it right.
I mostly work with Rigid resins so I can’t say much about the other ones.
I have tested all heat and timing of post cure and found nothing changes with warp. The geometry how the part is placed does help. It may help to do fine layers since that would probably set the resin more during the print.
That’s rather unfortunate…but I am pretty much at the same conclusion as well
I guess I’ll stick to non-heated cures for parts that don’t require the functional full mechanical properties…because that DOES prevent warping from my experience.
Yeah, not heating them does definitely reduce warping a lot but as you stated before that comes at the expense of less mechanical properties. If, for example, a Rigid resin needs to cure at 70/80 C, we cannot expect the same result without that kind of heat.
Totally. From some empirical testing UV only seems somewhere in between the stated green and UV+heat cured state in the datasheets.
Have you tried curing the part without heat, and then you put it in an oven at 70/80oC?
I know it sounds strange but maybe after a cold curing session it becomes immune to an afterward heat treatment.
Yup tried that - unfortunately doesn’t work. I also tried curing at lower temperature but still saw warping. I suspect this might help on some geometries, but I also suspect that the HDTs of these resins is so low that it’s hard to cure with heat without deformation occurring.
Are you using a Form 3 or 3L? What resin?
The resin where I have experienced dramatic curling is elastic resin. The way I significantly if not almost completely mitigated this was to not peel off the part from the build platform when washing, and to instead dunk the build platform into the form wash while the object is still adhered to it. This way, the raft won’t curl and it will prevent the object from curling.
After washing, I then peel off the object and put it in my form cure. If you’re still getting peeling at the curing stage, consider if you can super glue the raft onto a steel plate small enough to fit in the form cure (since the build platform is too large I believe? But if it does fit then try sticking that in there? Though you don’t want resin to cure onto the build platform). If keeping the part adhered to a platform while curing helps but doesn’t completely solve the issue, consider adding additional supports in addition to curing while adhered to the platform.
Hope this might help you, but not sure if it’s relevant to your exact issue.
I have been experiencing warping issues as well. For reference, this part is 8" in length and .5" thick printed in biomed amber. What I’ve done to minimize warp was to keep it flat after curing (@ recommended time & temp) by placing a heavy object over it while it cools. This part was cured without supports in a large UV curebox from Wicked. I would also dried these parts in the green state for over a day.
The result significantly improved. There is slight warping when I place it on a granite plate, maybe 0.5mm deviation. This would be challenging to do if your part is not flat, but I suspect that if there is some sort of fixturing while the part cools, you will see an improvement. However this may vary with a different resin.
It’s not the amount of heat, but the rate of heating. Similar to metals and ceramics, you want to ramp up the heat slowly, like 1 degree every 5 minutes level of slowly. Warping comes from a heat gradient where a warmer portion of material expands more than a cooler portion. Same, but reverse, on cooling. You need to maintain a low temperature gradient within the part. I’m not aware of a solution using form’s cure chamber, but one workaround would be to use a second heated enclosure to slowly heat the part to 70*C over multiple hours, and once the part is heated, then stick it in a preheated cure chamber. Then return the part to the dedicated heat chamber to slowly bring the temperature back down to room temps.
I appreciate you sharing your experience in minimizing part warping during post-curing. Keeping parts physically held in place (during post-curing or while cooling) could certainly help, as well as heating and cooling parts more gradually. I also wanted to pass along Best practices for post-curing prints which includes some advice for post-curing based on part geometry.
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