Factors Affecting Speed - Extrusion System

One of the factors affecting the printing speed - extrusion system, common extrusion system includes extruder, stepper motor, throat, heat sink, nozzle.

Extruder

Extruders are divided into Direct extruder and Broden extruder, and although the basic principle is the same - using an extruder to push the filament through a heated nozzle - the difference is where the extruder is located. Both designs have the same result, but there are some consequences to the different designs.

Direct extrusion is more accurate than Broden extrusion in controlling the amount of filament fed and more accurate in retraction; it requires relatively less torque from the extrusion stepper motor; it makes it easier to change filament; it is more suitable to print soft materials such as TPU; however, it has a heavier nozzle and high inertia when the movement is done, and these factors are not good for fast printing.

Broden extruder nozzle is lightweight and has low inertia, so it can move  faster; the nozzle and extruder are separated, making it easy to maintain. However, the filament and PTFE tube have some elasticity, resulting in a greater distance and speed required for retraction, which is not as accurate as near-range extrusion retraction; the section of filament in the feed tube is more difficult to use up.

Compare the advantages and disadvantages of them, Athough the Direct extruder has advantages in the weight of the nozzle, but its weaknesses in extrusion stability is also deadly; for Direct extruder, while there are disadvantages, but in the case of weight reduction can reduce its disadvantages, and its advantages are obviously what we wanted, and in the case of having the same extrusion force, the Direct extruder can achieve higher printing speed, so choose to use a lightweight Direct extruder for high-speed printing is a better selection.

Throat

The throat is the device that connects the extruder with the nozzles. When printing at high speed, we often need better thermal isolation performance and stability, which means that the lower part needs higher temperature and the upper part needs timely cooling, so that the throat can keep the upper cold and the lower hot to achieve a more accurate retraction and avoid the phenomenon of " blocking" when extruding filaments. Choosing the right throat can bring you a better printing experience. (For example, the V400 uses a Phaetus throat that has the thermal isolation and stability we need, and a smoother inner wall which reduces friction between the filaments and the throat, making it easier to extrude and retraction the filaments, and making the filaments more uniform)

Therefore, every aspect of the extrusion system is closely linked to speed, with lighter moving weight Direct extruder, high temperature resistant all-metal throats, higher thermal conductivity and larger heated volume nozzles all contributing to high speed printing!