PETG vs. PLA: Differences and Comparison
Learn more about the differences between these two materials and the advantages and uses of each.
PLA and PETG are two thermoplastics we often see in the 3D printing space. While Xometry only directly offers PLA at this time, it's important to know what options are out there so you can make an informed decision. So what are PLA and PETG, what's so different about them, and what are their applications? In this article, we'll be digging into the details of both materials to help you get answers to these questions and decide if Xometry's PLA offering is good for you. We'll also explore some potential alternatives you may not have considered.
PLA Definition and Comparison to PETG
PLA was first discovered in the 1930s at a DuPont lab, but was not commercialized until the 1980s by Cargill Inc. PLA is a polymer that is essentially a polyester, related to PET. The lactic acid source material can be derived from a number of natural and renewable sources such as corn starch and sugar cane. PLA was specifically commercialized as a “green” substitute for PET. This is due to PLA being made from renewable materials and having the characteristic of degrading quickly. PLA also makes an excellent filament for desktop and hobbyist FDM 3D printers, as it has a relatively low melting point and very low viscosity at the nozzle and cools to a hard and resilient finish.
To learn more, see our guide on What is PLA Material.
Advantages of PLA Compared to PETG
Here are a few things we like about PLA and where it has an advantage over PETG:
- It's easier to achieve higher cosmetic quality using PLA with FDM printers.
- PLA is more environmentally friendly than PETG.
- PLA requires a lower temperature to melt, making it compatible with a wider range of machines.
- It is easier to post-process and hand-finish prints made with PLA than PETG.
Disadvantages of PLA Compared to PETG
There are some downsides PLA has when compared to PETG. A few of them are listed below:
- PLA is weaker and more prone to fracture than PETG.
- Inter-layer bonding of PLA is poorer. PLA parts are more anisotropic than those made from PETG.
- PLA parts are susceptible to moisture and UV and are less temperature stable than those made from PETG.
- PLA is stiff and more brittle than PETG, making it more likely to fail when being bent or twisted.
PETG Definition and Comparison to PLA
PET or polyester (DuPont Dacron) was first discovered in 1931. It was commercialized as Terylene, stretched sheet material, and for blow-molded bottles in the succeeding years. The "G" in PETG comes from the addition of the glycol group (PETG – PETGlycol), which improves the thermal properties by making a less uniform polymer chain. This addition results in a lower melting point and lowers residual stress from cooling. Unlike PLA, which can be made from renewable sources, PETG is manufactured from crude oil-derived materials. To learn more, see our guide on What is PETG.
Advantages of PETG Compared to PLA
There are some benefits to using PETG instead of PLA including:
- PETG is more flexible, allowing it to bend and flex further than PLA before failing.
- PETG is more chemically stable than PLA.
- PETG has higher impact strength than PLA, reducing the risk of fracture.
- PETG is a harder material than PLA, making it more abrasion-resistant.
Disadvantages of PETG Compared to PLA
There are some disadvantages to using PETG, such as:
- The higher hardness of PETG is double-sided; while being more resistant to abrasions, that also means it's more difficult to smooth via sanding.
- PETG requires higher bed and nozzle temperatures, which contributes to machine wear and longer warm-up and cool-down cycles.
- Due to its higher viscosity, PETG is more prone to stringing. This can reduce the cosmetic quality of the parts and require slower printing.
- PETG tends to be more expensive per kilogram than PLA.
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| Attribute | PETG | PLA |
|---|---|---|
Attribute Typical Tensile Strength (Yield) | PETG 50 MPa | PLA 57.4 MPa |
Attribute Typical Elongation at Break % | PETG ~130% | PLA 1.9%-4% |
Attribute Cosmetic Quality | PETG Fair | PLA Excellent |
Attribute Tendency to String or Ooze | PETG High | PLA Low |
Attribute Typical Cost per Kilogram | PETG $15–$25 per kg | PLA $12–$20 per kg |
Attribute Easy to Sand/Post-Process | PETG No | PLA Yes |
Note: Chart values are for reference only and are based on data from various providers. For more specific information, see manufacturer-provided data sheets.
In the section below, you'll find the most common questions and comparisons we get asked when it comes to PLA and PETG.
Common Comparisons Between PLA and PETG
Applications
PETG is better for ductile, wear-resistant, and chemical-resistant applications. Models with moving parts and contact against other components will be more resilient in PETG. Parts that will experience either water, sunlight, or heat exposure will also be better in PETG. PLA is better suited to low-stress cosmetic applications and components that require a better finish quality.
Part Accuracy
PLA is better suited to maintaining part precision. This is because of its better printability and lower chance of warping. It should be noted, however, that under steady load, PLA tends to creep. For smaller features, PETG bonds better, as it is more viscous in the melt state and has better layer-to-layer adhesion.
Printing Speed
When it comes to print speed, PLA has PETG beat. This is because PLA prints at lower temperatures and is less viscous or sticky, allowing higher print speeds to be achieved. With PETG, things need to be slowed down a bit since the material needs more time to extrude and successfully bond to prior layers. There are also longer warm-up and cool-down periods for PETG due to the higher print temperatures involved, which adds to the total cycle time.
Surface Finish
Both materials can produce similar surface finish quality. However, due to PLA's lower viscosity, it's easier to achieve a smoother-looking model off the machine. This also means you will be less likely to have unwanted strings or fibers of material with PLA, resulting in a better finish.
Heat Resistance
PETG has a considerably higher melting point, typically between 220 and 250 °C. PLA, on the other hand, usually melts between 180 and 210 °C. While this makes PLA easier to extrude, it also means parts made from it won't be as temperature-resistant as parts made of PETG.
Biodegradability
PETG is derived from crude oil and is environmentally stable. Its life in landfills is measured in centuries. In comparison, PLA is a fragile polymer derived from more renewable and natural sources, making it a more biodegradable and environmentally friendly option. Don't be fooled, though; it can still take decades for PLA to degrade naturally. In ideal conditions, such as at industrial composting facilities, that time frame can be shortened to months or even weeks.
Material Cost
PETG has a typical cost range of $15 to $25 per kg. Standard PLA, on the other hand, costs around $12 to $20 per kg. Pricing depends on the material class, supplier, and volume purchased and is subject to change.
Christian Tsu-Raun, Team Lead, Manual Quoting, at Xometry says, "PLA is a bioplastic made from a variety of plant-based materials originally developed as a biodegradable plastic for single use and other applications. Desirable 3D printing attributes are rigidity, low cost, and speed of printing. PETG is a polyester, with glycol added to stabilize it and lower the melting temperature. It is recyclable but not biodegradable and is more resistant to a variety of chemicals. Desirable 3D printing attributes of PETG are increased thermal resistance, durability and flexibility. Xometry started offering PLA as a low-cost material intended for fit and form prototyping, while relying on our fleet of Stratasys Fortus printers for functional prints due to improved strength and consistency. PETG is not currently supported on the Fortus systems but our PC and PCABS materials are similar."
Mutual Alternatives to PETG and PLA
There are plenty of other thermoplastics out there that can be used with FDM 3D printing. Below are some mutual alternatives to both PETG and PLA you may want to consider:
- ABS: Acrylonitrile butadiene styrene (ABS) is a popular alternative to both PETG and PLA. It can produce good quality, high-strength models. Although the risk of warping is higher, especially for desktop machines, and an enclosed build chamber should be used, increasing the difficulty level to work with it. At Xometry, one of our most popular general-purpose FDM materials is ABS-M30.
- ASA: Acrylonitrile styrene acrylate (ASA) is related to ABS, except it's specially formulated for greater UV resistance, making it ideal for outdoor use. We offer ASA in a wide range of color options.
- PC: Polycarbonate (PC) is another material we offer and is also a great alternative to PETG and PLA when you need a material with superior impact resistance, strength, and chemical compatibility. However, it can be much more challenging to work with due to its very high extrusion temperature requirements, among other factors. At Xometry, we use industrial machines that can handle the task without problem, but it may be more difficult for machines that fall into the desktop or hobbyist category.
Similarities between PETG and PLA
PETG and PLA do have significant similarities, which are :
- Both materials should be within the capability range of most machines despite the higher extrusion temperatures of PETG.
- They can both be transparent or colored. Xometry's standard color offering for PLA is red, blue, black, and white.
- They are both relatively affordable materials and common choices for prototypes and models.
Summary
This article compared PETG and PLA as a material for use in 3D printing applications. We hope the information will prove useful to you as you make decisions about your next project.
If you prefer to let someone else handle the hassles of 3D printing, or you don't have access to a 3D printer, we've got you covered! You can upload your 3D files to the Xometry Instant Quoting Engine® and get instant pricing and lead times on PLA and dozens of other 3D printing materials across the various processes we offer.
Disclaimer
The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.