Keeping PLA material from warping after a print
Printer: MK3S
Filament: eSun PLA+ 1.75mm (Yellow)
I had some parts printed and went to assemble them outside since it was a nice sunny day (75° - 80° F). The parts were sitting in direct sunlight for maybe an hour while I was working on them. However, when I came back inside once I was done, I noticed that most all the parts had warped significantly. (That was my bad; I was dumb and forgot to factor in what the sun/heat would to do plastic. Lesson learned)
Going forward, besides avoiding direct sunlight/excessive heat, is there anything that can be applied like a coating of superglue, epoxy, spray-paint, etc. that would help give the prints more protection from warping in the sunlight/heat?
Thanks everyone. Loving the community. Very informative.
Best Answer by bobstro:
Even coated, the internal structure is likely to deform. The glass transition temperature is the temp at which plastic will deform before actually melting. PLA has a glass transition temperature (Tg) of around 60C/140F, so it's relatively easy to get it to soften in outdoor conditions. You're probably better off with a filament that won't deform at such low temperatures. PETG is typically rated at around 80C/176F. Colorfabb nGen to around 85C/185F and HT to 100C/212F. You can a variety of other filaments that are rated up to over 100C/212F but they can be trickier to print. Most will fare better than PLA. UV degradation is another consideration.
RE: Keeping PLA material from warping after a print
Even coated, the internal structure is likely to deform. The glass transition temperature is the temp at which plastic will deform before actually melting. PLA has a glass transition temperature (Tg) of around 60C/140F, so it's relatively easy to get it to soften in outdoor conditions. You're probably better off with a filament that won't deform at such low temperatures. PETG is typically rated at around 80C/176F. Colorfabb nGen to around 85C/185F and HT to 100C/212F. You can a variety of other filaments that are rated up to over 100C/212F but they can be trickier to print. Most will fare better than PLA. UV degradation is another consideration.
RE: Keeping PLA material from warping after a print
I've read tidbits about annealing printed PLA parts to add strength. I've tried it with smaller parts, a few times accidentally; can't say I've had positive outcomes. But the finished parts are a lot harder and much less flexible. I'd think they'd be less susceptible to further thermal stress. But doing an anneal and keeping the part "intact" may pose the biggest challenge. Shrinkage during anneal is the second hurdle.
RE: Keeping PLA material from warping after a print
Thank you very much @bobstro and @Tim for the information!
RE: Keeping PLA material from warping after a print
Good materials for high temperature use are cellulose lactides and certain grades of polylactide.
Cellulose lactides will usually stand 100°C without annealing and up to 140°C after annealing, high temperature polylactides almost always need annealing for temperatures over 55°C, but after annealing can match the annealed Cellulose lactides.
The only two brands of Cellulose lactides of which I know: Extrudr (Greentec & Greentec Pro) and Fillamentun (NonOilen).
All these are almost as easy to print as conventional polylactides (they just need a little higher nozzle temp).
RE: Keeping PLA material from warping after a print
@xanthe
But the anneal part of the equation is the difficult-to-do-correctly operation. Even these compounds will shrink, warp and otherwise deform during the anneal. The end result - in my experience, is a sturdy part that doesn't really look like what was printed.
What's missing is the anneal temperature profile. How fast to raise the temperature, how long to hold at temp, and how slowly the part needs to cool. And the actual expected shrinkage if the anneal profile is followed. All this info is needed to successfully anneal a part.