3D printer extruder

A Bowden extruder is a type of filament feeding mechanism used in many FDM 3d printers that pushes filament though a long and flexible PTFE (Teflon) tube to the hot end. An alternative type of extruder which is also widely used in filament 3D printers is the direct drive extruder or direct extruder, which sits closer to the extruder hot end.
Advantages.
Bowden type extruders are easier to swap since they are outside the print head. They also have less chance of tangling the filament while it unwinds from the spool. Additionally, they reduce the mass of the extrusion carriage because it doesn't have to hold a stepper motor. This allows for faster changes in print head movement direction, increased print speed, increased accuracy, and decreased instances of artifacting or ghosting along the x and y axes.
Disadvantages.
One disadvantage is that because Bowden extruders push filament through a long and curved tube, more friction must be overcome compared with direct drive extruders. To partially mitigate these friction forces, the tube is made of PTFE, which has a low coefficient of friction. Flexible filaments do not print well because the filament flexes inside the tube and clogs up the machine.
Another disadvantage is that the feeding distance is relatively long, and thus the resistance is high, meaning the stepping motor of extrusion is required to have a higher torque. 