Cooling is an essential part for prints to finish successfully. Not only do motors and other parts need to be cooled to prevent overheating, but the barrel and print itself often require active cooling.
Stepper Motor Cooling
While these motors are designed to run hot, there is a limit to how hot you want them to get for prolonged periods. One of the simplest ways to cool your components without disrupting the operation of the overall system is to add passive heat sinks. These heat sinks will increase the heat dissipation of the individual components by expanding the area available for convective heat transfer.
The majority of FDM printers will have a fan on the barrel to prevent heat creep and frustrating nozzle clogs. When plastic material is being melted to extrude through the nozzle, that heat will often travel up the plastic filament strip. This heat will cause the filament to expand. If this expansion occurs in the middle of the barrel, the filament will get a large bulge, one too large to pass into the hotend or to be pulled out of the extruder. This often leads to a clog that requires the disassembly of the extruder. To prevent this, a barrel cooling fan is needed.
Active Cooling refers to a fan actively blowing on the print as each layer is laid down. This process is needed for high surface quality on PLA prints and similar materials. This can actually be a negative to use on larger ABS prints due to its shrinkage rates. You have to know what material you are printing in and what settings that particular filament prefers.
Active cooling, and often the barrel fan, will require the firmware on your printer to be flashed with correct PID settings. Without this, an active cooling fan can actually cause the nozzle to cool – often enough to cause a print to fail.