What is PETG vs PLA for 3D Printing

Introduction

As the most used two 3D printer filament in 3D printing community, it is important to get a comprehensive knowledge of PLA and PETG.

• PETG and PLA are very common 3D printing materials, both of which have unique properties that are very popular among 3D printing enthusiasts and manufacturers.
• PETG and PLA are two completely different types of plastics. PLA, or polylactic acid, is a biodegradable thermoplastic derived from renewable resources, while PETG, or polyethylene terephthalate glycol, is a glycol-modified version of PET, the same material commonly used in plastic bottles.
• Choosing the right filament is crucial due to factors such as the material being printed, the temperature at which the print will be used, and the stresses that will be put on the print, such as bending or twisting.

Understanding PLA (Polylactic Acid)

What is PLA?

• PLA,or polylactic acid, is a biodegradable thermoplastic derived from renewable resources such as corn starch or sugarcane. Known for its ease of use, low printing temperature, and minimal warping, PLA is often the go-to filament for beginners and those seeking high-detail, aesthetically pleasing prints. Its eco-friendly nature also appeals to environmentally conscious users, making it a staple in educational settings and artistic applications.

Properties of PLA

• PLA has moderate tensile strength and is suitable for nonfunctional and artistic parts. PLA generally has lower flexural strength compared to other materials such as PETG or ABS. Its glass transition phase is around 60 to 65°C, and it can soften and deform at temperatures above 60°C. PLA has low thermal expansion and minimal warping.
• PLA is considered one of the easiest filaments to print with and is suitable for beginners. Due to its composition, it has minimal warping and good bed adhesion. The bed temperature for this type of filament is generally around 60 ℃. The fumes emitted by PLA are minimal and only occur during printing, but they do emit some nano-particles, which is why ventilation is required. PLA usually does not pose a health hazard. Un-melted filament is non-toxic and is suitable for educational and home environments.

What are Advantages of PLA

• PLA is great for beginners in 3D printing due to its low melting temperature compared to other materials. It also requires less maintenance to prevent moisture absorption, depending on the environment where it is stored.
• PLA is suitable for fine detail projects but is not ideal for vapor smoothing. However, if printed on a standard machine at low speeds of around 60 mm/s, it can produce very shiny, smooth prints without post-processing.
• PLA is eco-friendly and biodegradable under certain conditions. Biodegradability typically takes place in a high-temperature environment inside a bioreactor. It can also biodegrade slightly when exposed to sunlight for extended periods.

What are the Disadvantages of PLA

• The main disadvantage of PLA plastic is its lower heat resistance. At temperatures around 200°C, PLA will melt, and at lower temperatures, it can become soft and pliable to the point of deformation.
• PLA tends to be more brittle than other types of filaments. This brittleness can sometimes be compensated for with additional wall layers in the print to make it stronger, but high impacts might cause it to shatter.
• Since PLA is an organic, biodegradable material, excessive UV light exposure will make it more brittle and cause it to crumble apart over time. This usually takes a long time and can sometimes discolor the plastic. Variations in PLA can occur from one company to another due to differences in the plastic and colorants used. Some colorants are less prone to fading than others.

Understanding PETG (Polyethylene Terephthalate Glycol)

What is PETG?

• PETG, or polyethylene terephthalate glycol, is a glycol-modified version of PET, the same material commonly used in plastic bottles. PETG is renowned for its superior strength, durability, and flexibility compared to PLA, while still maintaining ease of use. It offers better chemical resistance and higher temperature tolerance, making it suitable for functional parts and outdoor applications. PETG's balance of toughness and print-ability positions it as a versatile choice for a wide range of projects.

Properties of PETG

• The tensile strength of PETG is much higher than PLA, providing excellent strength and functional use for mechanical parts. Its good balance of strength and flexibility makes it more resistant to cracking under stress. Its melting point is around 220 to 250℃.
• Printing properties and ease of use are a bit more challenging than PLA but easier than ABS. PETG requires some fine-tuning and settings to get it to print correctly. The bed temperature should be around 70 to 90℃ to improve adhesion and reduce warping. It adheres well to surfaces like glass, and using PEI sheets or Kapton tape can also help with adhesion. PETG is less prone to warping compared to ABS and behaves more like PLA during printing. Its superior strength makes it suitable for mechanical parts and high-stress applications. Its flexibility makes it far less brittle than PLA, and it has very good impact resistance. It does not shatter like PLA, making it ideal for parts that endure stress and strain.
• With its excellent transparency and dyeability, PETG can be used to create lampshades, decorative items and artworks.

Advantages of PETG

• PETG offers significantly better heat resistance than PLA. It can withstand higher temperatures without deforming or warping, with a glass transition temperature (Tg) ranging from 70-80°C (158-176°F). PETG's melting point is higher as well, typically around 220-250°C (428-482°F). This higher heat tolerance makes PETG suitable for applications where parts may be exposed to higher temperatures during use or processing.
• The cost of PETG filament is low than most of 3D printer filaments, even PLA filament.
• PETG has excellent UV resistance and doesn't degrade or discolor easily in sunlight. It is more UV stable than ABS. This property making it an ideal choice for outdoor applications. 

Disadvantages of PETG

• PETG, while offering superior strength and heat resistance compared to PLA, does require more attention to printing settings and bed adhesion to achieve optimal results.
• Slightly more challenging to print compared to PLA
• Tendency to stringing and oozing during printing
• Requires careful management of bed adhesion

Comparing PETG and PLA

Printability

• Both PETG and PLA are generally considered easy to print. PLA typically requires a lower print bed and nozzle temperature compared to PETG. Both materials are not very prone to warping or stringing.
• The ideal printer settings for PETG and PLA are quite similar. PLA's average print temperature is around 200°C, while PETG requires a slightly higher temperature, typically between 210 and 220°C. The print speed is similar for both materials since they both exhibit minimal warping. However, PETG benefits from a slightly higher print bed temperature of around 70°C, whereas PLA's print bed temperature is usually around 60°C.
• PETG is easy string in 3D printing. So, you need to be careful to set a precise print parameter from print tests.

Mechanical Properties

• The strength and durability of PLA and PETG differ slightly. PLA has a tendency to shatter when impacted hard enough, whereas PETG is more impact-resistant. The mechanical properties vary as well; PLA tends to shatter under stress, while PETG stretches and flexes.
• PLA is generally stiffer compared to PETG, which is more flexible and offers higher impact resistance.
• Both filaments are suitable for different environments and applications. PLA is well-suited for decorative and some low-stress functional prints, while PETG excels in higher temperature applications and is more durable, less prone to shattering. This makes PETG ideal for mechanical parts.
• It's important to note that PLA can be modified by add other material to make its properties more better. The toughness of most PLA+ are much better than original PLA.

 PLA VS PETG  source: Bambu Lab

Observation of the elongation at break data for Bambulab PLA confirms that Bambulab's PLA is in fact PLA+. The toughness of PLA+ can surpass PETG.
The toughest PLA+ can have an elongation at break of up to 20%, that is far more than PETG.

Environmental Impact

• PLA is known for being biodegradable under specific conditions, typically requiring industrial composting facilities with controlled temperature, moisture, and microbial activity. This process breaks down PLA into simpler compounds over time, contributing to its eco-friendly reputation. Additionally, PLA is recyclable through mechanical recycling processes where it is shredded, melted, and extruded into new filament, reducing waste and promoting sustainability in 3D printing.
• In contrast, PETG does not biodegrade naturally but is highly recyclable. It undergoes a similar recycling process to PLA, where it is ground into pellets and remelted for reuse. This recycling capability makes PETG a viable option for environmentally conscious projects, supporting circular economy principles by minimizing plastic waste.
• When using PLA and PETG in 3D printing, environmental considerations include ensuring adequate ventilation to mitigate emissions and proper disposal practices. Recycling initiatives for 3D prints, support structures, and failed prototypes are increasingly available, facilitated by specialized companies that collect and process these materials. These efforts contribute to reducing the environmental footprint of additive manufacturing processes.

Use Cases for PLA

Best Applications for PLA

• PLA is best suited for prototyping and low-stress parts. It is also excellent for decorative items and figurines, making use of its resistance to warping for precision prints. PLA's ease of use makes it perfect for educational projects and beginner prints.

Specific Examples

• PLA is commonly used for printing a variety of items such as toys, scale models, artistic sculptures, and some low-stress mechanical parts. Its ease of printing and vibrant color options make it ideal for creating detailed and aesthetically pleasing objects. PLA's ability to maintain dimensional stability and resistance to warping ensures high precision in prints, making it a versatile choice for hobbyists, educators, and professionals alike.

Use Cases for PETG

Best Applications for PETG

• PETG is particularly well-suited for functional parts and high-stress components due to its superior durability and impact resistance. It excels in outdoor applications that require exposure to sunlight, as it maintains its strength and structural integrity over time. Additionally, PETG's chemical resistance makes it suitable for applications where exposure to various chemicals is a concern, further extending its versatility in engineering and industrial settings.

Polyethylene Terephthalate Glycol (PETG) is a versatile thermoplastic widely used in various industries due to its strength, transparency, and ease of fabrication. Here are specific examples of its applications:

• Mechanical and Functional Parts: PETG is preferred for gears, pulleys, brackets, and mounts due to its excellent strength and flexibility. These parts can withstand mechanical stress and provide reliable performance over time.
• Prototyping: Engineers and designers use PETG for prototyping because it can endure functional testing and stress without breaking. Its durability ensures that prototypes can accurately simulate real-world conditions.
• Art and Decorative Objects: Artists utilize PETG to create sculptures and models due to its translucency, which can achieve aesthetically pleasing effects such as a stained glass appearance with certain types of filament. This makes PETG suitable for creating intricate and visually appealing artworks.
• Consumer Electronics Casings and Housings: PETG is ideal for printing durable and visually appealing casings and housings for custom electronic projects. It offers both functional strength and aesthetic appeal, making it a popular choice for creating protective covers, enclosures, and accessories like watch bands and smartphone cases.
• Educational Models: Educators prefer PETG for educational models and teaching aids because of its durability and safety. PETG prints are robust enough to withstand handling by students while maintaining detailed features essential for educational demonstrations.
• Automotive Parts: PETG is used in automotive applications for custom car parts and accessories such as dashboard mounts and clips. Its resistance to impact and temperature changes ensures that parts remain reliable and functional in diverse automotive environments.

How to Choose Between PETG and PLA？

• Project Requirements: Evaluate the specific needs of your project. If you require high strength, durability, and flexibility, PETG may be preferable due to its superior mechanical properties compared to PLA. Consider the environment in which the printed object will be used; PETG is more resistant to chemicals and suitable for outdoor applications exposed to sunlight.
• Printer Capabilities: Check if your 3D printer can handle the chosen filament. PETG typically requires higher printing temperatures (around 220-250°C) and a heated print bed (around 70-80°C) compared to PLA (typically around 190-220°C for nozzle and 50-60°C for bed). Ensure your printer's temperature settings and bed material (such as glass or PEI) are compatible with the filament to achieve successful prints.
• User Experience: Consider your own experience and comfort level with different materials. PLA is known for its ease of use, minimal warping, and low printing temperatures, making it ideal for beginners and educational purposes. PETG, while more challenging to print due to potential issues like stringing and bed adhesion, offers greater durability and versatility for functional prints.

By carefully assessing these factors—project requirements, printer capabilities, and your own experience—you can make an informed decision between PETG and PLA that aligns with your specific needs and ensures successful 3D printing outcomes.

Conclusion

• Choosing between PETG and PLA depends heavily on the specific requirements of each project. Factors such as durability needs, environmental conditions, and desired mechanical properties play crucial roles in deciding which filament to use. Sometimes, the best approach is to experiment with both materials to determine which one best meets your project's requirements.
• Additionally, recycling 3D prints is becoming increasingly important for sustainability. Open-source tools like the ArtMe3D filament extruder (available at https://www.artme-3d.de/) provide a practical solution to recycle old prints and failed prototypes into new filament. This not only reduces waste but also lowers the overall cost of filament procurement, making it a viable option for environmentally conscious makers and businesses.
• By leveraging such tools, 3D printing enthusiasts can contribute to a more sustainable approach to manufacturing while exploring the versatility and benefits of different filaments like PETG and PLA for their projects.

FAQs

What are the main differences between PLA and PETG?

• Environmental Impact: PLA (Polylactic Acid) is biodegradable under certain conditions, such as in industrial composting facilities. PETG (Polyethylene Terephthalate Glycol), a synthetic plastic, is not readily biodegradable.
• Physical Properties: PLA has a lower melting temperature and can be more brittle, making it prone to shattering. PETG, with a higher melting point, is more durable and less likely to break.
• Printing Characteristics: PLA is easier to print due to its lower melting temperature. PETG requires higher temperatures and is more resistant to impact and heat.

Is PLA actually plastic?

Yes, PLA (Polylactic Acid) is a type of plastic. It is a biodegradable thermoplastic derived from renewable resources like corn starch or sugarcane.

What is PETG good for?

PETG (Polyethylene Terephthalate Glycol) is good for creating durable, impact-resistant, and chemically resistant objects. It is often used for 3D printing functional parts, mechanical components, and containers.

Is PETG better than PLA?

Whether PETG is better than PLA depends on the application. PETG is stronger, more durable, and more chemically resistant than PLA, but PLA is easier to print, more biodegradable, and has a lower melting temperature.