Print Thickness vs. Heat Resistance

Effect of Print Thickness on Heat Resistance

When 3D printing, layer height and part thickness can influence more than just strength and weight. The thickness of a print plays an important role in how well it holds its shape under heat, whether during service use or during post-processing such as annealing. Heat deflection temperature (HDT) is often discussed when comparing materials, but the print’s geometry and density also have a large effect on real-world performance.

Thin Prints and Heat Deformation

Thin-walled or low-density prints are more prone to warping and deformation when exposed to heat. Because the structure has less material to resist internal stresses, it will soften faster and lose its shape more easily. This is especially noticeable when annealing thin models since the plastic relaxes as internal stresses are released.

For this reason, extra measures should be taken when working with and annealing thin parts. Two common methods are salt annealing or sand annealing, where the print is buried in fine grains to hold it in place while it heats. If the print is flat, placing a weight on top can help keep it from bowing or curling during the process. These methods reduce unwanted distortion and allow the heat treatment to improve thermal resistance without losing dimensional accuracy.

Thick Prints and Dimensional Stability

Thicker, denser parts behave differently under heat. Because they have greater bulk and structural integrity, they are more resistant to softening and warping during exposure. A heavy, solid print will generally hold its shape without needing to be supported during annealing. While the annealing process can still improve heat resistance by increasing crystallinity in certain materials, the odds of geometric deformation are much lower compared to thin-walled prints.

Beyond Heat Deflection Temperature

The heat resistance of a printed object cannot be determined by material rating alone. While HDT gives useful baseline information, geometry and thickness contribute to how that object will perform in practice. A thin tray and a solid block made of the same filament can show very different behaviors when placed under heat. Understanding this relationship makes it possible to choose the right print settings, infill, and post-processing method to get the desired thermal performance.