Main elements of an extruder

The coldend and the hotend are the main components of an extruder. The first serves to feed the material while the second expels it.

Cold end

The cold end is made up of various components, such as a spring tensioner and a winding gear. These components are used to guide the flow of the material. The cold end is powered by a DC motor designed to drive the movement of the 3D printer’s filament. It can achieve high accuracy and deliver maximum torque at low speeds.

Hot end

The hot end is the part of the 3D printer responsible for depositing the molten material on the printing end. During the 3D printing process, the material would have to pass through a heated chamber before it can be deposited in a liquid state layer by layer. For a 3D printer, a feed tube is used to feed the material into the melting chamber which is usually Teflon coated metal. The hot end nozzle is a small piece designed to channel the flow of molten material. It is usually available in different sizes and is attached to the heater block.

Types of extruder

The extruder has two different types depending on the unit. These are the direct extruder and the Bowden extruder.

Direct extruder

Direct extruders use the cold end and the hot end together in a single block. This method allows the molten material to pass directly through the melting chamber. Direct extruders are known to produce sharper prints due to their shorter distance between the hot end and the drive mechanism. This feature makes them more reactive to retraction and extrusion. In addition, the shorter distance between the hot end and the drive mechanism facilitates printing with flexible materials. However, since the direct extruders are connected to the hot end, they can also displace their mass. This could cause issues like backlash, overshoot, and frame wobble.

Bowden extruder

In the case of a Bowden extruder, the cold end and the hot end are not connected to each other. Instead, a tube is used to connect them. This method eliminates the need for the two parts to be linked together. It allows the 3D printer to produce better and more accurate prints due to the absence of vibrations and slowdowns. The main problem with a Bowden extruder is that it can get stuck in the stretching and retracting stages. Furthermore, since the cold end and the hot end are distant from each other, this could cause an increase in the system hysteresis.

3D printing technologies that require an extruder

Different 3D printing methods require the use of the extruder and some of these include the direct type, others instead the Bowden one.

FDM

FDM 3D printers use material extrusion to create cross-sectional objects. This process involves the melting of the material and then the extension through a nozzle.

Casting of binder

Some 3D printing companies use a binder jet printer to create a 3D object by adding a binding agent to the powder.

Common extrusion problems you may encounter

The following are common extrusion problems that you may encounter during printing.

Under-extrusion

Sometimes, under-extrusion occurs when the 3D printer is unable to supply the right amount of material. This problem can cause the levels to be missing or holes in the levels, which can make the project appear incomplete. This can be remedied by checking the machine settings (such as layer height, speed and extruded quantity, etc.).

Over-extrusion

This problem can cause various problems, such as inaccuracy, smearing and stringing. It negatively affects the quality of 3D prints. It is solved by optimizing the retraction values.

Conclusion

Understanding the various components of the extruder of a 3D printer is very important since this is where the actual printing process takes place. Most 3D printers use this component. If you’re looking for 3D printing assistance, keep following us for other helpful tips.