Glossary · Part

3D printing

Part cooling fan

The fan on the print head that blows directly onto the freshly printed material so that it solidifies quickly. Important for overhangs, bridges and fine details.

Explained in more detail

The part cooling fan sits on the print head and blows over a nozzle or an air duct onto the layer that has just been laid. It is not to be confused with the hotend fan, which cools the heat sink above the melt zone and must always run. How strongly the part cooling fan should run depends on the material: PLA usually with full cooling, PETG and TPU medium, ABS, ASA, PA and PC only a little, so that the layers bond well and the corners do not lift. The first layers are usually printed without cooling. Many fast printers also have a side or chamber fan that blows on the part from the outside.

Where does the term come from?

In English it is called part cooling fan, and in the slicer often just "fan" or "cooling" with a percentage.

In practice

• You set the fan strength in the slicer's filament profile, separately for normal layers, overhangs and bridges.
• If the part cooling fan fails, overhangs curl upwards and fine tips deform. A short test with an overhang model shows this quickly.
• With ABS and ASA in an enclosed build volume, cool lightly: too much air promotes warping and cracks between the layers.

Not to be confused

Not to be confused with the hotend fan (heatsink fan), which must not be switched off, or with the enclosure or filter fan, which moves the air in the build volume.

Frequently asked questions

How fast should the part cooling fan run for PLA?

Usually at 100%, from the second or third layer. The first layer adheres better without cooling.

Why is my print brittle along the layers?

The cooling is often too strong for the material, especially with ABS, ASA, PA and PC. Reduce the fans and, if necessary, print slightly hotter.