Have you ever struggled with material selection when 3D printing? PLA and PETG are two of the most commonly discussed materials. PLA filament is the first choice for many 3D printing enthusiasts and beginners due to its low price and easy printing. PETG filament stands out in functional printing due to its excellent strength and durability.
Although both have their own advantages in use, their mechanical properties, printing performance and applicable scenarios are different. This article will analyze the differences between PLA and PETG in detail from these aspects to help you make more accurate material selection based on your specific printing needs.
Material Definition of PLA and PETG
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PLA (Polylactic Acid): a biodegradable thermoplastic derived from renewable resources like corn starch or sugarcane. As a PLA filament used in 3D printers, it’s melted and extruded through a nozzle to form precise layers, creating everything from artistic models to functional prototypes. Known as PLA plastic filament, it’s celebrated for its ease of use, affordability, and eco-friendly properties, making it a staple in PLA 3D printers worldwide.
Recommended reading: What is PLA Filament?
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PETG (Polyethylene Terephthalate Glycol-modified): It is a transparent thermoplastic with good heat and chemical resistance. It is a modified material of PET (polyethylene terephthalate) and G (glycol), which has better toughness and transparency than standard PET. PETG filament has become a commonly used material in functional printing due to its excellent strength, impact resistance and high temperature resistance, and is particularly suitable for making prints that require strong mechanical properties and durability.
Material Properties: PLA vs PETG
- Tensile Strength: PETG typically ranges from 55-60 MPa, while PLA is around 40-60 MPa, making PETG less likely to break under tension.
- Impact Resistance: PETG is more impact-resistant, suitable for parts that may face sudden forces.
- Heat Resistance: PETG withstands higher temperatures (up to 80°C) compared to PLA (around 60°C).
- UV Resistance: PETG is more UV-resistant, ideal for outdoor use, while PLA may fade or degrade in sunlight.
- Flexibility: PETG is more flexible, reducing cracking, but PLA is more rigid, holding shape better in some cases.
- Chemical Resistance: PETG has better resistance to chemicals, useful for parts exposed to solvents.
- Moisture Absorption: PETG absorbs moisture faster than PLA, leading to issues like bubbling, stringing, or layer splitting if stored improperly. Always keep PETG in an airtight container with desiccant. PLA is less hygroscopic but still benefits from dry storage.
Recommended reading: How to Dry Filament: PLA, ABS ,TPU & Nylon
| Property | PETG | PLA |
|---|---|---|
| Tensile Strength | 55-60 MPa | 40-60 MPa |
| Impact Resistance | High, suitable for drops | Lower, more brittle |
| Heat Resistance | Up to 80°C | Around 60°C |
| UV Resistance | High, good for outdoors | Low, may fade in sunlight |
| Flexibility | More flexible, less cracking | Rigid, holds shape better |
| Chemical Resistance | Better, resists solvents | Lower, less resistant |
| Moisture Absorption | Easier to absorb moisture | Low hygroscopicity but still needs careful storage. |
Printing Performance: PETG vs PLA
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Temperature Requirements: PLA requires lower nozzle temperatures (180-210°C) and bed temperatures (50-60°C), making it easier on printers. PETG, needing higher temperatures (nozzle 210-250°C, bed 70-90°C), may challenge some setups but offers better layer adhesion.
- Warping and Bed Adhesion: Both materials generally have good bed adhesion, but PETG may warp more, requiring careful calibration. PLA's minimal warping makes it more forgiving for beginners.
- Stringing and Oozing: PETG is more prone to stringing, necessitating retraction adjustments, while PLA is less affected, enhancing print cleanliness. To minimize stringing with PETG, users can adjust retraction distance and speed, or experiment with different printing speeds and temperatures.
- Layer Adhesion: PETG's superior layer adhesion reduces delamination risks, making it suitable for functional parts, whereas PLA may have weaker interlayer bonds over time. PETG's better layer adhesion might be due to its higher printing temperature, allowing for better fusion between layers.
Applications
When it comes to material selection, the final decision often depends on the intended use of the product. Generally speaking, if the project only requires rapid prototyping, concept verification or artistic creation, then PLA is a good choice because it is low-cost, easy to print and has excellent detail performance, which is suitable for scenarios where durability is not required.
When the design needs to withstand greater mechanical stress and long-term exposure to high temperature or humidity, PETG is more suitable. Its excellent heat resistance, water resistance and chemical corrosion resistance make it the material of choice for manufacturing functional products such as industrial parts, mechanical components or food packaging containers. PETG has been widely used to produce waterproof and durable containers (such as plastic bottles), which also verifies its safe contact with food and reflects its important position in global plastic manufacturing.
It is worth mentioning that although both PLA and PETG are used in certain industries (such as food, medicine, costume props and decorative parts), their respective characteristics make them each have their strengths in actual production. For example, PETG's water and heat resistance makes it more suitable for engineering products that require long-term, stable performance, while PLA is often used in fields that require fine appearance and creative expression because it is easy to process (such as painting and polishing) and can be mixed with other materials to produce a variety of textures.
COST
For users who are keen on 3D printing, cost is always a key factor in determining the feasibility of the project. According to market data, the price per kilogram of PLA is about 20 to 30 US dollars, while PETG is slightly higher, at 25 to 35 US dollars. Although prices fluctuate depending on the brand and quality level, overall, users with tighter budgets tend to choose lower-cost PLA. However, PETG's higher pricing also reflects its significant advantages in durability, heat resistance, and chemical corrosion resistance, making it more suitable for scenes that require higher functional parts.
Post Processing
Cleaning
Both PETG and PLA prints should be cleaned with isopropyl alcohol to remove any residue from printing, such as support material or excess filament. For PETG, cleaning may require extra attention due to potential stringing or oozing during printing, which can leave thin strands that need careful removal. PLA, being less prone to stringing, typically has cleaner prints, making this step straightforward.
Sanding
Sanding is essential for smoothing surfaces and removing layer lines. PLA, due to its rigidity, is easier to sand with fine-grit sandpaper (e.g., 200-400 grit), allowing for a uniform finish. PETG's flexibility can make sanding uneven areas challenging, as the material may deform under pressure, requiring more patience and possibly multiple grits to achieve a smooth surface.
Painting
Painting enhances aesthetics and can be done with acrylic paints for both materials. PLA's rigid surface allows for direct painting with good adhesion, making it ideal for decorative projects. PETG, however, may need priming to improve paint adhesion due to its smoother, more flexible surface, which can repel paint without preparation.
Sealing
For food-related applications, both materials must be sealed to prevent bacterial growth due to their porous nature. PLA can be sealed with food-grade epoxy or resin, and its rigidity makes it easier to apply evenly. PETG also requires sealing, but its flexibility may require more care to ensure complete coverage, especially for complex geometries. Both materials can be considered food-safe 3D printer filaments when properly sealed, addressing the need for "food grade 3D filament" in applications like kitchenware.
Heat Smoothing
An interesting finding is that PETG's higher heat resistance (up to 80°C) makes it suitable for heat smoothing, where the print is exposed to controlled heat to melt layer lines for a glossy finish. PLA, with a heat resistance of around 60°C, risks deformation during this process, limiting its use for heat smoothing and highlighting the difference between PLA and PETG in post-processing options.
In conclusion
Choose PLA filament for ease of printing, cost-effectiveness, and aesthetic projects like decorations or prototypes, especially for beginners. Choose PETG filament for strength, durability, and resistance, ideal for functional parts and outdoor use, with attention to printing settings.
Frequently Asked Questions
Q: Is PETG stronger than PLA?
A: Yes, PETG is stronger than PLA due to its higher impact resistance, better flexibility, and superior durability. While their tensile strengths are similar, PETG's toughness and resistance to heat, UV, and chemicals make it the better choice for functional and high-stress applications.
Q: Can i print PLA and PETG at the same time?
A:It is not recommended to print PLA and PETG at the same time. Because their printing temperature and bed temperature requirements are different, it will cause adhesion and print quality issues.
Q: Are PETG and PLA filaments food safe 3d printer filaments?
A:PLA and PETG may meet food safety standards, but the 3D printed products are not suitable for direct contact with food. This is because the layers of FDM printing are prone to accumulate bacteria and are difficult to clean thoroughly. At the same time, many printing filaments contain non-food grade dyes or additives. In addition, the brass nozzles of ordinary 3D printers may contain lead, further increasing the risk of food contamination.