I spent the weekend trying out heat treating some of my PLA filament (see my blog article on the sous vide method). I wanted to see how some of the different heat treating temperatures affected my basic PLA material as well as some of the more expensive "tough" PLA that I had used.
Sometimes I observe expensive materials test out at very low strengths, even when heat treated. Without adjusting the print settings and heat treat temps to correctly optimize the material defaults can sometimes be pretty far off on some of these unique blends.
Following the default print settings for example, this Tough PLA material failed at 25 MPa due to poor layer delamination. In comparison my cheapest basic PLA achieved an average of 48 MPa before heat treat. Changing nozzle and heat treat temps is needed to optimize the material's strength and toughness.
This is certainly not an exhaustive set of tests and many variables could still be explored. I think my biggest take-away here was just the importance of testing the specific material and print settings. There are so many variables in 3D printing, especially for a hobbyist. Many of the advertised material properties will not be achieved without proper process control and adjustments.
Moving forward I will always print a quick ASTM D638 tensile sample whenever I setup a new 3D printed project. It's a quick and cheap way to verify your process and material before you commit to the print, especially on large parts with expensive material.