How Print Temperature Affects PET-CF Strength – 3D-Fuel

Print temperature has a bigger effect on PET-CF than on most filaments. Independent testing by Scott at Edge of 3D shows how much.

The results

Scott printed a full test set at 285°C (the middle of our previous 280–290°C recommendation) and again at 305°C, then annealed a second 305°C set. All loads are in kilograms of force; higher is stronger.

Test	285°C	305°C	305°C, annealed
Tensile yield, X axis	221 kg	283 kg	332 kg
Layer adhesion	38 kg	106–117 kg	Slightly lower than unannealed
Direct thread pull-out	57 kg	64 kg	83 kg
Heat-set insert pull-out	116 kg	127 kg	141 kg
Impact (Izod)	Highest	Lower	Lowest

What it means

Print hot for strength. Raising the nozzle 20°C nearly tripled layer adhesion and improved every strength test.
Annealing adds stiffness and strength. Tensile, thread, and insert strength all went up after annealing.
There's a trade-off in toughness. Higher print temperatures and annealing both make PET-CF more brittle, so it absorbs less energy in an impact.

Heat resistance

Scott also measured how hot printed test bridges could get before sagging in his oven:

Printed at 280–290°C, unannealed: about 105–112°C
Printed at 300°C or hotter, unannealed: a jump of roughly 100°C, to about 228°C at 305°C
Annealed (any print temperature from 280 to 320°C): about 240–250°C

His oven test isn't the same as a standard heat deflection test, so compare these numbers to each other, not to datasheets. Our datasheet lists a service temperature of 125°C unannealed.

Test conditions

Voron 2.4, 0.2 mm layers, no part-cooling fan, bed at 90–105°C. Your results will vary with your printer and settings.

See Annealing PET-CF.