Does baking your 3d prints make them stronger?

We’ve read that popping PLA prints in the oven for 15 minutes at 100°C will make them stronger. This process is properly called “annealing”. But does it work for PLA? And how much extra strength does it give? We decided to find out.

My intuition is that heating a 3d print could improve adhesion between the layers, so we’ll test strength by pulling apart in this direction.

I downloaded some strength testing pieces from Thingverse, and printed 6 of them at 210°C in our premium PLA.

Here they are lined up like soldiers ready for battle.

Then we put 3 of the 6 in the oven for 15 minutes at 100°C.

Finally, we set up a sophisticated tension test rig. I’m not sure how accurate our spring based meter is, but that doesn’t matter much, since we care more about the difference between annealed and non-annealed PLA, not about absolute values of strength.

And the results?

Un-annealed PLA broke at 11, 10 and 9.5kg of tension. Annealed PLA broke at 8.5kg, 6kg, and 5kg. So that’s a surprise! Annealing appears to make the layer adhesion worse!

We’d be interested to hear from anyone else who has tried this experiment.

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