What is Infill for PETG Printing?

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In the world of 3D printing, we have two surfaces; the first is the outer surface or the wall, and the second is the internal surface or infill. Obviously, 3D printing lets us have complete control over every aspect of the objects inside and outside or perimeters.

We have access to all dimensions of an object. It is a huge revolution against traditional injection molding. In the latter one, we had no access to the infill and internal surface; this problem has been solved with the help of infill in 3D printing. With 3D printing, we can have 3D objects.

All plastic objects around us, from bottles to plastic dolls, are made by 3D printing. This revolutionary invention happened in the 1830s in Japan. From that day up to now, many developments have taken place in the world of 3D printing.

The very first raw materials being used for 3D printing were PLA and ABS but, then PTE (Polyethylene terephthalate) came on the scene; by recent developments in the area, a higher version of PTE, which is called PTEG (Polyethylene terephthalate glycol) came up. In this article, we will focus on infill in regard to PETG.

What is Infill for PETG Printing

What’s the Difference between PET and PETG?

One may think that PET and PETG are similar to each other. But it should be mentioned that there are some differences between these two on a molecular level. PET is the result of two monomers combining. PETG may involve these same monomers but also includes glycol, giving it different chemical properties than PET.

In comparison to PET, you can rely more on PETG for manufacturing bottles since the results will be highly flexible. Another two property of PETG is that this polymer can highly resist shocks and also, you can use it for higher temperatures.

What is Infill?

There exist two distinct zones in 3D printing, the shell and the fill (infill). The process is also called filament consumption. Infill is the density of the material used in printing. If we consider the density of plastics as a spectrum, the lowest density is called hollow part (0%) and the highest density is the totally solid part (100%) which the latter one bears the highest costs.

In addition to the cost, more time is needed for producing thick objects. The density also affects the weight of objects too. More density results in heavier objects. Buoyancy is also directly affected by the amount of infill. We control the amount of infill by G-code instructions (it is a language for computers).

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Infill density 

The normal percentage of density is 20%. Based on the usage, the percentage of infill varies. A good test for the amount of density is whether the object is touchable or not.

For example, for decorative objects, like vases, even no filament is ok, since they will never be under pressure, but for other tools, like mechanical tools which bear heavy stress, there needs to be a high density.

  • Luxurious tools: There is no need to use a great deal of infill for objects that only need to look good (dolls, vases, sculptures), so these things need the least infill up to 15%.

  • Standard: A mixture of average stability and filament is seen in the materials with 20-50 percent of infill.

  • Robust: Total solids are the objects that need the highest density. (100%). They are usually mechanical tools needing strong stability.

Infill pattern

Patterns are basically made of lines and zigzags, making more complex shapes. There is a huge number of infill patterns, but the most famous and frequently used patterns are Rectangular, Triangular or Diagonal, Wiggle and Honeycomb, Cubic, Cubic subdivision, Octet, gyroid, Tri-hexagonal, and grid.

Obviously, the more lines a pattern has, the more density ithas. Simplify3D, Cura3D, Slic3r are the most known software in this regard. With the mentioned software, we select the size and dimensions of the objects we want.


If you are looking for another type of infill that is both fast and simple, Grid is the one. In contrast to rectilinear, you will be given the ability to print it in both directions due to the rotation angle of 90° in each layer.

This way, material accumulates in spots where the paths cross. The grid infill is more solid (and has better layer adhesion) than the rectilinear infill. If the nozzle goes over the crossings where material accumulates, you can expect concerning noises from the printer. In another case, you can expect that the machine will fail.


This infill prints a grid made of hexagons. There are two main advantages to this: mechanical resistance and optimal paths without crossings. Unfortunately, there is a disadvantage to the use of this infill and that is related to the high consumption of materials (about 25%) in comparison to other infills.

Moreover, you can expect an increase in the printing time, almost twice the time of the above-described options.

More about PETG 

Polyethylene terephthalate glycol is a polymer widely used in the 3D printing industry. It is famous for its unique characteristics; good temperature resistance, durability and resistance, good adhesion between layers, little deformation during printing, resistance to environments with low temperatures for long periods of time, chemical resistance (bases and acids), and the absence of odor during printing, and recyclability made it the number one raw material in 3D printing.

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It is a safe material for plastic food dishes. Since it is recyclable, it is earth-friendly.


In comparison to plastic materials such as acrylic or polycarbonate, we came to believe that PETG is the most efficient and cost-effective material. There is a good reason why this material is so popular with high-strength display units and also, impact-resistant glazing. PETG’s qualities make it unique and preferable over other materials.

One of the uses of PETG is in the food industry due to fact that it doesn’t contaminate the food and also, this material is completely recyclable. For example, it is utilized for making food containers.

You can use two methods to form PETG products either with heat and vacuum. In addition, the products will be highly resistant to pressure, meaning they will not crack easily. Using the molding process, the industries are able to turn PETG material into various shapes and sheets.

Along with the above-mentioned uses, due to easy thermoforming and chemical resistance, this material is also used for manufacturing drinking bottles that can be either used one time or multiple times. In addition, PETG has also medical and clinical uses due to its exceptional properties, rigid structure. For this reason, scientists are using this material to manufacture implants, medical device packaging, etc.

At the same time, PETG is extremely strong and has great chemical resistance. This allows it to print objects that can sustain high temperatures, food-safe applications, and exceptional impact.

In addition to its uses in the medical and food industries, PETG is also used in businesses too, believe it or not for making point-of-sale stands and different types of retail displays. Practically, one can use PETG for creating numerous shapes and colors that businesses can use to create signage that no customer will miss.

Moreover, PETG can be easily printed, and therefore, it enables business owners to create customized and eye-catching designs that will also help them save money in both the short-term and long term.

Due to the unique features of PETG, it is now widely used in the 3D printing industry. It is a developer version of former polymers. Features such as good temperature resistance, durability, and resistance, good adhesion between layers, little deformation during printing, resistance to environments with low temperatures for long periods of time, chemical resistance and etc. made it a number one choice for users.