PETG filament: top tips for successful prints

Having trouble deciding which material is best for a project that requires ease of printing and good durability? Then definitely check PETG! PETG combines the best of both worlds: easy printing and exceptional resistance. Capable of withstanding temperatures of up to 80°C and offering a shiny, smooth finish, this material is perfect for creating everything from robust mechanical parts to elegant decorative objects. Read our blog for the best tips for printing with PETG filament.

Why is PETG filament so interesting?

If we compare PETG with other 3D printing materials such as PLA and ABS, we will find that PETG combines the properties of these two materials. On the one hand, we have ease of printing, and on the other, industrial-grade durability. These two properties of two different materials are combined in one filament – PETG. Objects printed from this material can withstand temperatures up to 80°C, it does not curl during printing and the finished products have a nice shiny surface. In light of the versatile nature of PETG, the demand can touch applications like mechanical parts, enclosures, decorative objects, and even EU-compliant food-safe projects.

Our PETG filament is a piece of engineering that has been deliberately designed to display an amazing combination of overall elasticity, strength, and durability.

Why should someone go for PETG instead of PLA?

One of the most common questions is whether PETG is stronger than PLA. It is indeed. Compared to PLA, PETG is tougher, and more resistant to the impact of forces, so using it is the best solution for parts subject to mechanical pressure. While offering a very long list of applications such as robotics, prosthetics and tools, one just cannot miss the fact that both PETG and PLA are basically soft materials and the latter might be the easiest to 3D print. Meanwhile, PETG which is stronger and more robust is like PLA, but for practical surfaces like robots, prosthetics, and tools.

Printing parameters

There are many factors that are important for high-quality prints from PETG and one of them is the right set-up and settings for the printer. Below is a list explaining the key parameters in detail.

Extrusion temperature

Most printers can print PETG within the 220°C to 240°C range. Printing below the recommended temperature range may result in poor bonding of the layers and separation of the printed parts while printing at higher temperatures may lead to the formation of strings and ugly blobs of melted materials on the part.

Bed temperature

To get the best possible adhesion of the first layer it is recommended to set the print bed at 80°C. PETG prints nicely on surfaces like glass or PEI sheets, however using some sort of glue spray for example 3DLac helps to avoid prints detaching mid-print.  This also avoids the excessive glueing that can destroy the build surface which can happen when using glue sticks.

Print speed

To reduce the defects, the print speed should be kept in the range of 60mm/s. But if you have a newer and more powerful printer, you can print PETG up to 200mm/s. If the printer is driven at a print speed that is too high, the prints made especially with fine details also tend to have layer adhesion problems.

Layer cooling

While PETG does not always require a cooling fan, it is practical to run a fan at a low-speed setting (approximately 20-40%) especially for printed models with overhangs or complex details, to improve the bonding of the layers without affecting adhesion.

Common problems and solutions when printing with PETG

Although print settings may seem appropriate, PETG prints may sometimes go wrong. Below are some issues along with troubleshooting tips:

Stringing

Most print results containing PETG will have some stringing, for this reason, it is often not the best material for high-temperature 3D printing. In order to minimise the stringing, a longer retraction distance should be set (try starting with 5mm) and the speed of the retraction motion should be reduced. In addition, increasing the retraction temperature closer to the low-temperature edge of PETG will help marginally.

Warping

In principle, PETG does not have many problems with warping compared to ABS. This problem can still occur if we are printing larger projects or if our printing pad is poorly or insufficiently heated. It is always recommended to heat the printing pad to 80°C and to calibrate the first layer well.

Bed adhesion

If you’re having trouble sticking to the bed, check the cleanliness and flatness of the base. We always recommend applying a thin layer of adhesive such as 3Dlac as this prevents it from coming off mid-print and allows for easier removal from the substrate when your print is complete.

Blobs and zits

These can occur in instances where the extrusion temperature of PETG is excessive. Many of these blemishes can be reduced by slightly lowering the print temperature and modifying the retraction settings.

PETG enhanced applications

PETG is not only limited to plain 3D prints because of its exceptional attributes but rather goes on to do the following:

Medicine

PETG has many good applications within the realms of mechanical and biomedical, providing strength with flexibility for medical prototypes and parts, such as prosthetics. Biocompatibility extends the use of PETG to non-implantable medical aids like prosthetic parts, dental devices, custom braces, and additional items employed in laboratories and research to support test devices and medical model applications.

Custom electronics enclosures

When it comes to manufacturing electronics enclosures, their durability and heat resistance are very important. PETG offers just that. Heat or humidity will not affect the stability of the PETG housing. It is also resistant to moderate temperatures, which further increases the safety of the case and helps with heat resistance.

Signage and display cases

Since PETG can also have a transparent surface, it is used in the production of durable signs. This is possible due to its UV resistance compared to other materials, thus preventing yellowing and degradation of characters even on external surfaces.

Functional prototyping for automotive parts

As a result of its impact resistance as well as its flexibility, this material is a great choice for functional prototype projects for automotive parts. In creating prototypes of testing conditions and equipment air circulation paths, PETG is used to make prototypes for air ducts as well as some sensor covering shells and other structural protective parts.

Protective gear and equipment

It is ideal for making facial shields, goggles, and other safety devices that are meant to last longer and not break due to the construction material, which is resistant to shattering. Again, the other aim for the use of PETG is in cases where durability is of utmost importance.

Is PETG Flexible?

Compared to the more rigid filaments like PLA, PETG only exhibits a medium level of flexibility. In other words, flexibility is balanced with toughness to enable this material to absorb impacts without cracking. Such a feature is suitable for rigid parts as well as flexible components, such as clips or springs.

Frequently asked questions

How do you get a smooth top layer on PETG?

The settings to get a smooth top layer with PETG involve the optimization of print settings.

• Slowing the speed of printing for top layers up to 20-40mm/s will ensure even extrusion and, more importantly, better layer bonding.
• Increase the number of top layers because usually in a range of 5-8 this should fill the gaps and give a much smoother surface.
• Lower extrusion temperature slightly to avoid stringing, and blabbing yet can still stick to each layer. A usual ideal temperature is within the range of 220-235°C.
• If necessary, apply ironing – a process where the nozzle travels over the last layer, with minimal extrusion, and tugging material for surface evenness. This can result in an extremely glossy and smooth surface.

What is the best nozzle for printing PETG?

While PETG can be printed using a variety of nozzles, a 0.4mm nozzle is commonly recommended for a balance of detail and speed. This size provides good layer adhesion and detail for most prints. However, it’s worth noting that larger nozzle sizes (like 0.6mm) can also be used effectively, particularly for larger prints where speed is more critical. The main consideration is to ensure the nozzle is clean and free from any obstructions, as PETG can be prone to stringing if the flow is inconsistent​.

What are the most common challenges when printing with PETG?

PETG tends to string and ooze during printing. It does this because it must have relatively high temperatures to extrude correctly, as well as for good layer adhesion. Another challenge is sensitivity to moisture; if this filament sits around absorbing humidity, it will also cause inconsistent extrusion. Minimising these problems can be achieved by optimising retraction settings, using dry filament, and regulating print speed and cooling. 

Why is my PETG not printing cleanly?

If PETG prints are coming out with imperfections, there may be a few reasons that this could be happening:

• Moisture in the filament: PETG is hygroscopic, meaning that it takes water in from the air. In case of taking too much water in, the filament can cause popping and bubbling and provide a rough surface. Store PETG in a dry box, and when necessary, dry before use.
• Temperature too high/low: The higher the temperature of extrusion, the more it will have stringing and blobs; on the other hand, at lower temperatures, it gives a poor bonding between layers. Start with the filament’s recommended range and adjust slightly to improve cleanliness.
• Incorrect retraction settings: Generally speaking, PETG is going to have to be retracted mid-level in order to avoid stringing without creating gaps in prints. Using a Bowden extruder, the retraction distance should be set at about 4-6 mm; using a direct drive, about 2-3 mm.
• Poor bed adhesion: If the bed adhesion is poor or inconsistent, this may be one of the reasons for layer misalignment. Go ahead and check that your bed is levelled, and put on an appropriate adhesive, such as a PEI sheet or light adhesive spray, for a better quality of the first layer.