All About PETG 3D Printing Filament： Materials, Properties, Definition

PETG 3D printing is the use of PETG (Polyethylene Terephthalate Glycol) (a thermoplastic material) as a build material for 3D printing, especially in FDM (Fused Deposition Modeling) printers. The “G” in PETG indicates that the glycol molecule in PET, a familiar material used in the production of plastic bottles, has been modified. PETG is one of the most popular 3D printing filaments thanks to its high impact strength, low haze, and good printability. For more information, see our guide to 3d printers.

Figure 1 below shows an example of PETG filaments:

The composition of PETG is derived from the composition of  polyethylene terephthalate (PET). They are similar in their chemical composition except for the fact that PETG has been enhanced by modifying its glycol content. PETG is formed by replacing ethylene glycol in PET with cyclohexanedimethanol (CHDM). This is what the “G” in PETG indicates. It is clearer, less brittle, and prints more easily compared to PET.

A PETG filament has certain properties that make it distinguishable from other filament materials, namely:

1. High chemical and impact resistance.
2. Good thermal stability.
3. It is a food-safe material.
4. Its extrusion temperature falls in the range of 220-260 °C.
5. It can be printed at a rate of about 40-60 mm/s.
6. The print bed must be heated to about 80 °C. Anything above this will lead to the warping of the print.

Comparison of PETG Filament Properties

Table 1 below highlights some common properties of PETG filament compared to other filament types:

PETG has a number of advantages that makes it good for 3D printing, including its high impact resistance, odorless fumes, and good thermal stability. There are still some disadvantages associated with PETG compared to ABS, however. PETG cannot be easily stored because of its high hygroscopicity. Another limitation of PETG is that it is difficult, if not impossible, to paint. ABS, on the other hand, is far more forgiving in this area: in fact, post-processing of ABS is relatively easy.

Why Is PETG Used in 3D Printing?

PETG is a highly beneficial thermoplastic printing material because it is versatile and easy to print. Due to its versatility, it is used by many 3D printing companies and private individuals alike for their printed models or parts. PETG is appreciated by many for its: hygroscopic, ease of printability, and smooth surface finish.

How To Use PETG in 3D Printing

Just like PLA, PETG is known for its ease of printability. If PETG filament is printed according to the manufacturer's and printer's recommendations, the resulting prints should meet the customer’s requirements. Here are some tips and tricks for 3D printing with PETG:

1. The temperature of the heated bed should be around 80-90 °C.
2. The melting or extrusion temperature should be anywhere from 220-260 °C. 
3. The hot end (the device responsible for melting the thermoplastic) does not have to be fully metallic. Hot ends with PTFE inner tubes can also be used.
4. Part quality can be improved by using layer fans. A layer fan is a small fan placed at the 3D printer head that cools the plastic once it is deposited.
5. To achieve good layer adhesion when printing with PETG, glass surfaces and adhesives such as hairspray should be used. If the PETG print is placed directly on glass, it is most likely going to stick too firmly to the glass surface – making it difficult to separate. Using adhesives ensures good adhesion while facilitating the easy separation of the print from the build surface.

Getting the PETG print settings right is fundamental to achieving a high-quality print. The retraction speed, for instance, determines how fast the melted filament is extruded from the hot end and nozzle. Getting the filament out of the nozzle as quickly as possible without compromising on the quality of the filament is important. Listed below in Table 2 are the recommended printer settings for PETG:

Generally speaking, thermoplastic materials with moderately strong materials, such as PETG, can be printed at wall thicknesses that fall in the range of 0.8-1.6mm. Nonetheless, it is possible to print thicker walls using a nozzle with a larger diameter. Thicker walls, in the range of 2-3 mm, can create parts with higher strength.

What Is a Good Wall Density for 3D Printing PETG?

A suitable infill density for PETG is 20%. The infill density determines how much of the filament material will be consumed in the entire printing process. A 20% infill is sufficient for non-functional parts such as prototypes and display models. The infill density can be increased but this would have a considerable impact on the printing cost and time. Infill density values range from 0%-100%. 0% will produce a hollow model while 100% will produce a totally solid model.

No, PETG is not biodegradable. PETG is an oil-based thermoplastic material and is non-biodegradable.

Yes, PETG is recyclable. It is one of the easiest thermoplastics to recycle. Many recycling programs accept this product and serve as evidence that it is eco-friendly.

Yes, PETG is hygroscopic. It has a strong affinity for moisture in the air. This property alone can have a negative impact on print quality. Exposing the filament to a humid environment will cause it to deteriorate faster. Storing PETG properly and using a filament dry box/ spool holder when printing helps avoid the filament from absorbing moisture.

What Is the Difference Between PETG and PLA in 3D Printing?

PETG is created from a thermoplastic material called PET. The G in PETG indicates that the glycol content in PET has been modified. PETG is 100% recyclable, though not biodegradable. PLA, on the other hand, is made from plant-based or natural materials such as corn. It is therefore both biodegradable (over time – about 80 years) AND recyclable. PETG is tougher and has better chemical and water resistance than PLA.

What Is the Difference Between PETG and PLA+ in 3D Printing?

PLA+ also called PLA Pro, Pro PLA (or PHA) is a superior version of PLA but the additives which were added to PLA to create PLA+ are unknown. Many manufacturers have refused to disclose information relating to this though some people speculate TPU – another thermoplastic filament – was used. Despite this improvement, PLA+ still comes behind PETG. PETG produces higher-strength parts than PLA+. However, PLA+ is biodegradable, making it a more eco-friendly product.

What Is the Difference Between PETG and PET in 3D Printing?

PET was created by combining two monomers. PETG still involves the same monomers though fundamentally it was created by modifying the glycol content of PET. PETG is better suited to higher temperatures and has better shock resistance than PET

This article presented PETG 3D printing filament, explained what it is, and discussed how it can be used for various 3D printed parts. To learn more about PETG 3D printing filament, contact a Xometry representative.

Xometry provides a wide range of manufacturing capabilities, including 3D printing and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.

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