Which of the following components helps cool the melted filament during 3D printing?

Fans play a crucial role in the 3D printing process, specifically in cooling the melted filament once it has been extruded through the nozzle. The extrusion process heats the filament to a temperature that allows it to flow and take shape, but it needs to cool quickly to solidify and maintain the desired shape and integrity as it builds layer upon layer.

The use of fans in 3D printers helps ensure that the filament solidifies uniformly, preventing issues such as warping or sagging, which can occur if the filament cools too slowly or unevenly. By directing air over the freshly printed layers, the fans contribute to a faster and more efficient cooling process. This is especially important for materials that are prone to warping.

In contrast, other components such as the filament spool serves primarily as the supply of the material, heat sinks are used to dissipate heat from the hotend but do not directly cool the filament, and cooling plates are not standard components in most 3D printers. Their functions do not directly contribute to the immediate cooling of the melted filament during the printing process as fans do.