What Is 3D Infill Printing?

3D printing allows you to control two aspects of your printer’s perimeters and infill. The walls will form the outer regions of this whilst the infill is whatever is situated within them.

Though only one has some control over the walls, the infull is far more dynamic and thus, play a key role in strengthening the weight and structure of the part. In 3D printing, you will have the ability to define a number of parameters that dictate the kind of infill that is utilized for a part.

These are set up in a slicer program when a 3D model has been translated into G-code. The most important parameters are infill density and infill pattern and this article will give you a better insight into the differences and similarities between these in order to provide you with a better understanding of how they work in 3D printing.

Infill differs from alternative traditional manufacturing methods of printing as it involves injection molding and subtractive manufacturing. The first of these involves inserting the relevant material into a mold in order to form a part.

The internal structure of this mold is not controllable and as a result, these parts are either solid or empty without any middle ground. Subtractive manufacturing, on the other hand, involves slicing material off of a larger part.

Similarly to the injection molding method, the infill cannot be adjusted without the interior being solid. Meanwhile, 3D printing involves extrusion of material in any form of pattern.


Infill density equates to the fullness of the interior part, In slicers, this is typically defined as a percentage situated between 0 and 100 with 0% meaning that a part is hollow.

The density has a significant impact on the weight of the part and the fuller the interior, the heavier the part is. Asides from weight, material consumption and buoyancy is also notably affected by the density of the part.

Some slicers will enable differing infill densities within the same part and this is known as a variable infill density. Using specified settings within the slicing program will allow you to highlight any density changes and make adjustments for specific areas of your print.

For the majority of standard prints, an infill density of 15-50% is highly recommended. This density ensures that the print time remains low and provides an adequate amount of strength whilst conserving material.

Functional prints, in particular, need to remain strong and it is therefore recommended to use a higher percentage of infill density for these prints (up to 100%!) Be prepared to use more patience in this instance as the end result will be well worth the wait.

For smaller models, consider using an infill density of 0-15%, This will result in a succinctly quick print that won’t use up too much filament whatsoever. Figuring models printed within this range will be lightweight and easy to break, so bear this in mind.


Infill patterns form the shape of the interior of a part. These can range from simplistic line patterns to more complicated geometrical shapes. Infill patterns will affect the weight, strength and flexibility of a part.

Across the various differing slicer programs, there are many different infill patterns. Like infill density, some of these are better for specific functions than others and the differing infill patterns have a wide range of attributes like material efficiency, complexity and the number of planes that constitute its connective strength.

For instance, a gyroid pattern connects the walls in three dimensions which inherently provides more strength. However, it is worth noting that this pattern occupies more material than other more simplistic patterns like lines.

Final Thoughts

To conclude, infill 3D printing equates to the density and pattern of a particular part. The infill plays a huge part in ensuring that the part is strengthened and solid.

When using a 3D printer, you will have far more options to determine the type of infill that you use for a part and this opens up the possibilities for endless creativity. Whilst simplistic line patterns may seem more appealing in order to simplify the process, gyroid patterns will be able to provide more strength due to the interconnectivity between the three wall dimensions. You may use more material in process but ultimately, the outcome will be a strengthened part which is only conducive in the long-term.

There are also a range of infills across a variety of slicer programs and you should research the particular infill that you are using during printing as this will provide you with more insight and the ability to tailor your printing to meet your individual needs.

Infills involve injection molding and subtractive manufacturing and it is also imperative to understand the processes behind both of these in order to obtain a deepened understanding into the role of the infill during the printing process. 3D printing provides better results than traditional methods of printing and you can also create your own 3D printer from scratch if you are somewhat of a printing enthusiast.

Alternatively, you can purchase a kit and build your 3D printer this way. Once you’ve got to grips with the basics of printing and the importance of the infill during the process, you will inherently have a deeper appreciation of the printing process.

Make sure that you are using the correct level of density in order to produce the results that you desire and also do not leave your printer unattended when constructing it as this can be a fire hazard if the nozzle of your printer becomes overly heated. Above all, always ensure that your 3D printer is maintained to a high standard and that any parts are replaced when required.

Michael Moore