In the process of 3D printing, Retraction is a very key setting, which directly affects the printing quality, especially in the model detail processing, surface finish and wire drawing. The "Retraction Distance" is one of the core parameters in the retraction setting. This paper will introduce in detail what is the draw-back distance, its function, and how to adjust it correctly to obtain better printing effect.

1. What is the distance between withdrawal and withdrawal?

Retraction refers to the phenomenon that when the nozzle moves (such as jumping to another printing position), the consumables are reversed to prevent the nozzle from dripping or drawing in the non-printing area. The withdrawal distance refers to the length of the consumable pulled back by the nozzle during withdrawal, usually in millimeters.

Simply put, when the nozzle needs to move when it is not printing, proper pumping back can avoid problems such as "wire drawing" and "material leakage"; The withdrawal distance determines the amount of consumables withdrawn by the nozzle.

Second, the role of pumping distance

1. Reduce the phenomenon of wire drawing: In FDM printing, if the drawing distance is too short, the molten consumables will easily pull out the filaments when the nozzle moves, which will affect the appearance of the model.
2. Prevent material leakage: Proper back pumping can effectively prevent the nozzle from dripping material during movement and keep the printing path clean.
3. Improve the printing quality: Reasonable drawing back setting can improve the detail expression and overall aesthetics of the model.

However, the greater the pumping distance, the better. If the withdrawal is too long, it may lead to nozzle blockage, poor extrusion, and even damage consumables during withdrawal, which will affect the printing effect.

Third, the pumping demand of different materials

Different printed materials have different requirements for back pumping:

-PLA: relatively rigid, suitable for medium pumping distance, generally recommended to be 1 ~ 3mm.
-ABS: The viscosity is high, and the pumping distance is slightly longer, and it is recommended to be 2~4 mm..
-PETG: It is sticky and easy to draw, and usually requires a higher withdrawal distance, which is recommended to be 3 ~ 6mm.
-TPU and other flexible materials: due to the soft material, too long back pumping is easy to cause material jam, so it is recommended to use short back pumping (0.5~2 mm) and short path with Bowden tube.

Fourth, how to adjust the pumping distance

Adjusting the pumping distance is usually carried out by slicing software, and common softwares such as Cura, PrusaSlicer, Simplify3D, etc. all provide relevant settings. The specific operation is as follows:

1. Open the slicing software and find the "Retraction" option in the "Extruder" or "Quality" settings.
2. Modify the value of "Retraction Distance".
3. Print the test model (such as a simple "Retraction Tower" or a model with a jump path).
4. Observe whether there is wire drawing or material leakage, and make fine adjustment according to the results.

V. Debugging suggestions

Users are advised to try from the recommended value, gradually increase or decrease, and observe the printing effect. For example, from 2 mm, gradually increase by 0.5mm until the wire drawing phenomenon disappears. At the same time, pay attention to observe whether there is poor extrusion or material jam.

In addition, the withdrawal speed will also affect the effect, which is usually set between 20 and 50 mm/s, and the best effect can be obtained when used in conjunction with the withdrawal distance.

VI. Conclusion

Reasonable adjustment of the pumping distance is an important means to improve the quality and detail expression of 3D printing. Different materials and different printer structures (such as direct extrusion and Bowden tube structure) have different requirements for back pumping, so users should constantly try and optimize the parameters according to the actual situation. Through careful debugging, wire drawing can be effectively reduced, model accuracy can be improved, and 3D printed works can be more perfect.

Mastering the adjustment method of pumping distance is not only a deep understanding of printing technology, but also a key step towards professional 3D printing.