Temperature and Cooling

Temperature and cooling are filament settings in most slicers, not print settings, because they depend on the material. There is no single right number: use the range the filament maker prints on the spool or its data sheet, and narrow it down with a test print.

Nozzle temperature: which way it pushes

UltiMaker calls printing temperature one of the most influential settings and describes both directions:

• Hotter: the plastic flows more easily, which suits thick layers and high speeds, and layers bond better. It also sags more on overhangs and strings more. Far too hot degrades the material and can clog the nozzle.
• Cooler: better control and cleaner overhangs, but a risk of under-extrusion and weaker bonds between layers.

Speed and temperature are linked: the faster you print, the more heat the plastic needs to melt in time (see Print Speed and Acceleration). A temperature that works at one speed may under-extrude at a higher one.

How to choose: Measure it OrcaSlicer's advice is to start with the filament maker's recommendation and then run a temperature calibration. Print a temperature tower across the maker's range and pick the temperature that gives the best mix of bonding, overhangs and stringing for the part you are making.

First layer temperature

Slicers set the first layer separately. UltiMaker says a slightly higher first-layer nozzle temperature improves adhesion to the build plate; OrcaSlicer warns it may also cause elephant's foot. Change it only if the first layer is not sticking after the usual fixes.

Bed temperature

UltiMaker says the ideal bed temperature is usually around the material's glass transition temperature, where it reduces shrinkage and warping. Too hot causes sagging and elephant's foot at the bottom of the part. Rule of thumb OrcaSlicer gives a guideline: take the glass transition temperature and subtract 5 to 10 °C as an upper limit. These two sources differ; when they disagree, the filament maker's printed bed range wins.

Where the settings are called what

What it controls	PrusaSlicer	OrcaSlicer	Cura
Nozzle temperature	Not confirmed	Not confirmed	Printing Temperature, Printing Temperature Initial Layer
Bed temperature	Not confirmed	Not confirmed	Build Plate Temperature
Fan never fully stops	Keep fan always on	Keep fan always on	Not confirmed
Fan range by layer time	Fan speed Min and Max, Enable fan if layer print time is below	Min fan speed threshold, Max fan speed threshold	Regular Fan Speed, Maximum Fan Speed, Regular/Maximum Fan Speed Threshold
No fan at the start	Disable fan for the first X layers	No cooling for the first	Initial Fan Speed, Regular Fan Speed at Height
Bridges and overhangs	Bridges fan speed	Overhangs and external bridges fan speed	Not confirmed
Slow down small layers	Slow down if layer print time is below, Min print speed	Slow printing down for better layer cooling, Min print speed	Minimum Layer Time, Minimum Speed

Not confirmed means we did not find the name in that slicer's documentation; the feature may still exist. In Cura, Enable Print Cooling turns the print head fans on or off. OrcaSlicer documents its nozzle and bed temperatures in the filament settings, with separate first-layer values and a bed value per plate type.

The part cooling fan

Prusa puts it plainly: each layer has to be printed on an already solid layer, and overhangs and bridges need cooling so the filament does not sag. More fan helps:

• Overhangs and bridges (see Overhang Droop). PrusaSlicer and OrcaSlicer can run a separate fan speed on these, which Prusa says is typically set higher than normal.
• Small layers and sharp tips, which otherwise get printed on plastic that is still soft.

More fan costs:

• Shrinkage and warping. UltiMaker says higher fan speeds cool better but can increase shrinkage. Prusa warns cooling can make warping or layer separation worse with some materials, and says Keep fan always on is typically on except for ABS, ASA, PC and some flexibles.
• First-layer adhesion. Prusa says the fan is typically disabled for the first 1 to 5 layers Rule of thumb to reduce warping and keep the print attached. UltiMaker notes a later full-speed height improves bed adhesion but can cause oozing and lower quality; it suggests full speed from about 0.5 mm is usually enough Rule of thumb, depending on material and layer heights.

How the fan follows layer time

Slicers scale the fan by how long a layer takes. Prusa's version: the fan runs at the minimum speed on long layers and the maximum on short ones, scaling in between. OrcaSlicer's thresholds work the same way, ramping between minimum and maximum as layer time falls. Short layers are where cooling matters, because the nozzle comes back to the same spot before it has set.

Minimum layer time: slowing down small layers

When even full fan is not enough, the slicer slows the layer down. Cura's Minimum Layer Time makes each layer take at least that long; UltiMaker notes lower values shorten print time but can deform small, detailed parts. A minimum speed stops it slowing too far: UltiMaker says too slow lowers nozzle pressure and hurts quality, and Prusa warns very slow printing for long periods can cause heat creep (see Heat Creep). Cura's Lift Head option moves the head away while it waits, giving the layer more time to cool.

OrcaSlicer's Don't slow down outer walls keeps the outer wall at its set speed, to avoid changes in shine and wall artifacts; the inner walls and infill then slow down more instead.

Enclosures and chamber temperature

OrcaSlicer notes that for ABS, ASA, PC and nylon a warmer chamber can reduce warping, while for PLA, PETG and TPU it suggests leaving chamber temperature at 0 to avoid clogs. UltiMaker adds that a warm build volume weakens the cooling fan's effect, so overhangs get worse. For the fumes from those materials, see FDM Emissions and Ventilation.

What to change first

1. Start inside the filament maker's range and run a temperature tower. Change temperature in small steps, one test at a time.
2. Overhangs droop, tips melt: more fan on overhangs, then a longer minimum layer time, then a few degrees cooler.
3. Layers split or crack, corners warp: less fan, a few degrees hotter, and for ABS and ASA an enclosure (see Warping).
4. Stringing: dry the filament first, then try a few degrees cooler within the range, then Retraction.