I did some experiments a while back with annealing PLA in a water bath (using a sous vide device from my kitchen). I made 4 test pieces and held 3 of them for 60 minutes at 70C, 80C, and 90C. Then I put all four pieces in a 210F oven with 85g tungsten weights on them. The unannealed piece deformed and the weight fell off after less than 10 minutes. The rest were pretty much stable for the next hour.
I used this technique to then anneal a garage door opener holder (printed in the same red PLA) for my car, which has survived for 1.5 years with 2 summers of hot sun parking.
@Paul_Gross
I was unfamiliar with annealing as well, so I looked it up: anneal: heat (metal or glass) and allow it to cool slowly, in order to remove internal stresses and toughen it.
@James_Kao No time to digest, but a casual search didn’t find water/air in the article. I could only think of water as brillant way to control the cooling rate.
This give more incentive to add higher temp heated chamber to the arsenal.
I didn’t use a bag, I just threw the parts into water. Using a sous vide bag would put compression on the parts while annealing, and leaving air in the bag would cause it to float since the parts are light.
No, my main purpose was to find a way to put my garage door opener holder back on service after it sagged and lost its grip on my car’s sun visor. Interestingly, while most types of plastics have easily findable water absorption rates (in terms of % increase after 24 hours of immersion), I couldn’t find any for PLA.
Brilliant observations, and thank you for sharing. After a discussion I had last week about pla disforming in boiling water I have jsed this to soften parts for push fits Eg onto a stepper shaft. This would definitely be usefull to add to that knowledge. Did you play with fill % and how did that affect it if not what fill did you print at.
I’ve used a heat gun to soften PLA and ABS to fine tune fitting parts. In this case, my only goal was to increase the heat resistance of the part. The garage door opener holder is a thin walled part similar to the test pieces and have no infill.
This is absolutely fascinating, I never would have guessed. I am quite familiar with annealing different metals (mainly silver and gold alloys), but who would have thought that plastics could be annealed?
I recently created a mandala out of PLA and softened it in boiling water in order to drape it over a plate, and after a few moment it handled like freshly boiled pasta. So annealing it in hottish water seems bizzarre and counter-intuitive. Oh well.
@Peter_Hertel it seems that an integral part of the process is the duration of the annealing, which in James’s case was an hour. You would presumably need to sustain the temperature between 70C and 90C for that time.
@shubham_bane Annealing is essentially heat-treating a meal or plastic in this case well below its melting point in order to alter its crystalline structure. With PLA, the benefits appear to be greater heat tolerance.
