annealing filigree parts?

I printed some new temples for my glasses out of Greentec Pro. The parts look and work fine, but i can easily bend them after heating them with hot tap water (about 60°C i guess). When bent to fit my head, the parts slowly revert to their old shape over the next few hours. I contacted Extrudr about this and they told me to anneal the parts at 140°C for two hours.
How can i do this without the parts losing their shape? The parts are thin (4*1.5mm) and curved in all dimensions. My best (untested) idea is to stick them in a pan filled with sand, heat it in the oven and leave it there until everything is cool again. Any other ideas?

Some sort of shell around it, water soluble casting plaster perhaps?

The sand idea may work.

I would maybe place it into something like a ziplock bag to prevent the sand from texturing the part unless you find that a desirable possibility.

I like Dust's suggestion too, but a fine sand would be easier to work with I'd be willing to bet.

The potential issue is the sand may stick to the plastic...

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Dust
The potential issue is the sand may stick to the plastic...

Not if you stick the part into a plastic zipper bag. Or vacuum bag.

Then put into bowl and pack with wet sand to ensure more homogenous heating.

I mean, in my minds eye I see this working pretty well.

Edited 1 time(s). Last edit at 04/22/2020 11:38AM by obelisk79.

please post results, good or bad

You could carve a shell in MDF.

OR

Just carry a thermos of hot water with you everywhere. When they lose their shape, dunk them in the thermos and remold them

Remolding frequently is what i do at the moment I don´t know how heat resistant ziplock bags are, maybe aluminum foil to keep the sand away?

Annealing PLA is done at 60C: [www.fargo3dprinting.com]
Ziplock bags are good up to 100C: [www.cnet.com]

foil would deform the surface of the print I still think a bad would be your best option.

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obelisk79
Annealing PLA is done at 60C: [www.fargo3dprinting.com]
Ziplock bags are good up to 100C: [www.cnet.com]
foil would deform the surface of the print I still think a bad would be your best option.

Ziplock bags are out then, i need about 140°C to anneal Greentec Pro.

Well crap. I can't believe I missed that information from the first post.

I just did a test run on a leftover part. Stuck the part in fine sand, put in the oven at 140°C for about 30min, then turned the oven off and let everything cool down.
I tested one of two identical parts, both sanded with 600 grit sandpaper. Surface looks exactly the same after annealing, no craters or stuck grains of sand. The annealed part no longer becomes soft in hot tap water. Now i´m running a load test on both parts to see whether the annealed part holds its shape...

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RaoulDuke
I contacted Extrudr about this and they told me to anneal the parts at 140°C for two hours.

I just noticed this is not exactly what they told me. They wrote 140°C for 20 minutes, then slowly cool over several hours. No idea how important slow cooling is, probably more so the thicker the parts are.

I put the finished parts in the oven yesterday. 140° for about 30min, covered in fine sand to avoid warping. Seems to work fine, after wearing them half a day they have held their shape well.