The importance of the layer fan

When talking about the functional parts of an FDM 3D printer, the layer fan is one of the most important components that can be found. A 3D printer usually has two fans in the HotEnd area, one in charge of cooling the HotEnd diffuser and another that cools the material that comes out of the nozzle. In this article we will talk about the latter, the layer fan.

When is it necessary

All users have tried to print some part with small area zones, where the nozzle is constantly moving in the same zone, a process that causes an excess of temperature that softens the part. The same happens when printing tall, slender parts, such as a small diameter cylinder, where heat accumulates in the same area and catastrophically deforms the part. Another typical deformation is that which occurs in very steep cantilevers, where the still hot material is deformed by the action of being suspended in the air, until it solidifies.

All these problems are solved simply by using the layer fan correctly.

Image 1: Small parts without and with layer fan.

Compatible materials

Before commenting on how to configure the layer fan, the user must take into account with what materials it is recommended to use the layer fan and with which not.

PLA

The PLA is the material par excellence that the layer fan needs, due to its low softening point. This means that if the nozzle is placed in the same area for short periods of time, the piece will suffer irreversible deformation. For this reason, the layer fan is a crucial component in all FDM 3D printers that use PLA or some composite material containing this polymer as a base.

ABS

This material and similar ones, such as ASA, are totally incompatible with the layer fan. This is because the ABS is very sensitive to the loss of temperature against drafts, such sharp increases that cause cracking (delamination of the layers) and the total failure of printing. For this reason, it is vital to use ABS and ASA with fully closed 3D printers. 

Others

Apart from the materials discussed above, in 3D FDM printing there are many more types of filaments and each with a different print configuration, for that reason a table with the majority of available materials is shown below and it is indicated if they need or no layer fan:

Table 1: Layer fan depending on the material.

Expert Advice

Once the user already knows whether or not he needs to use the layer fan, he must know how to use it and when.

At the beginning of a print the user needs the first layer to adhere to the base with sufficient firmness so that it does not peel off during printing. This is achieved, not only using some product that improves adhesion, but also keeping the temperature stable, so the layer fan must be turned off during the first two layers. Once the print has a certain height, the speed of the layer fan must be adjusted to the geometry of the piece in each layer. In general, there are two cases where the speed must be varied: when the printing time of a layer is greater than 5 seconds and when it is less than 5 seconds. In the first case, the layer fan speed must be increased linearly from 70% with layer times of 20 seconds or more, up to 100% with layers of 5 seconds. When the layer time is less than 5 seconds, the user must use the layer fan at 100% speed, sometimes being an insufficient speed that causes deformation in the part. This problem, which usually occurs when narrow and tall pieces are made, is solved by printing several separate pieces simultaneously as much as possible so that each layer has time to cool.

Any lamination software (Cura3D, Simplify3D, Slic3r...) allows you to modify the speed of the layer fan at the height of the piece that the user wants.

Image 2: Configure layer fan in Simplify3D. Source: Simplify3D.

Conclusion

It is important that all users of a 3D FDM printer know how to use the layer fan correctly, as it is a complement that elevates the quality and complexity of the parts.