[Stefan] is always trying to make stronger 3D prints. Annealing can strengthen prints, but often at the expense of the part’s exact dimensions. His latest approach is to embed the prints in plaster and then anneal in an attempt to fuse the plastic together without changing its shape or size. Did it work? See for yourself in the video below.
He’s done a lot of work we’ve taken note of before where he measures the strength of parts after different post-processing steps. His test plastic parts used both PLA and PETG.
In general, the parts were made with 100% infill to prevent the plastic from collapsing on itself during the heating process. Getting the plaster bubble-free took a few attempts. This isn’t a fast technique. The plaster had to be dry before annealing and even with a dehydrator, it was well over 36 hours before the parts were ready for the oven.
Getting the parts out of the plaster turned out to be harder than you’d think. Mechanically removing most of it and then washing away a little residue turned out to be the best way. The tests showed the PLA reference parts — those not treated — were stronger than the annealed parts. But the PETG parts were transformed and nearly three times as strong as they had been.
[Stefan] thinks that further drying of the plaster casts might result in even stronger PETG parts. Although the PLA parts were somewhat weaker, the annealed parts became much more temperature resistant, surviving 170 degree temperatures.
The only downside we see is that it isn’t a quick or simple process. But if you need stronger or more temperature resistant materials, this is very achievable with common equipment.