Annealing / Heat Treating High Temp PLA

Annealing is a heat process that changes the actually properties of a material. In the case of Proto-Pasta HT PLA, it makes the part you printed stronger and more temperature resistant (thus the High Temp bit of the name). It does this on a chemical level by increasing cross-linking between polymer chains.

Annealing can be used on other materials, such as PA Nylon and PPSU. Annealing PPSU causes it to increase ductility and reduce hardness, to avoid cracking and premature part failure. I won't cover these it this article.

Proto-pasta make a range of High Temp PLA filaments including:

• Semi transparent: Silver Smoke, Iridescent Ice and Coffee and Cinnamon, Start dust
• Solid Colours: Matte Fiber, Carbon Fibre and now Premium HTPLA v3 in White and Black

How?

By heating the finished part up to 60 – 110 °C and holding them there (time dependant on part size and temperature) you can raise the heat deflection temperature up to 170 degrees. This is much higher than PLA, PET and ABS which have heat deflection temperatures from 55 – 110 degrees.

Bilby 3D have been using Proto-Pasta High Temp PLA’s to manufacture a machine upgrade kit for months. The specific part sits against the 3D Printer heated bed. After annealing parts do not soften in the slightest sitting but against the 110oc heated bed for more than 20 hr long prints.

We use a food dehydrator (pictured right) with exact temperature controls. We anneal at 70 degrees for 4 hours. The parts do not deform or distort at all during this process. Larger parts have been baked for longer (up to 8hrs).

How Long do you bake the part?

If starting out use one of the transparent HT PLAs (like Silver smoke). It will change from transparent to opaque during annealing, so you will know if it is done. Then do the same part in something solid (like matte Fibre and bake for the same length of time).

Some people online have reported deforming during annealing. We think they are using too high temperatures. Consistence and low temperatures are key and our testing found household ovens do not maintain temperatures under 80 degrees very well at all.

Also allow them to cool in situ before handling.

We do not leave on supports as after treating the parts are much harder and stronger, and thus more difficult to finish. For that matter if you wanted to sand do that first also. his being said we can see how some pieces could benefit from keeping support on during annealing to reduce the likelyhood of warping.

See PLAHT