What is the function of a cooling fan in FDM printing?

The function of a cooling fan in Fused Deposition Modeling (FDM) printing is primarily to cool down the printed layers as they are deposited. When a filament is extruded from the hot nozzle, it is molten and forms a layer that needs to solidify quickly to maintain its shape and dimensional accuracy. The cooling fan helps in managing the temperature of the printed part, preventing it from warping or sagging due to excessive heat retention. This cooling process is crucial, especially for overhangs and intricate designs, where quick solidification ensures that the layer retains its intended structure before the next layer is added. Proper cooling aids in achieving better surface finish and overall print quality, reducing the likelihood of defects associated with thermal distortion.