3D printing with PLA vs. ABS: What's the difference?

PLA and ABS are the two most common materials for prototyping (desktop) FDM 3D printing (aside from, perhaps, PETG). As thermoplastics, both filaments enter a soft and moldable state when heated, returning to a solid-state when cooled. FDM printers melt and extrude PLA and ABS filament through a nozzle to build up parts layer by layer.

While both materials are used for FDM, they have key differences that make each more optimal for different applications. In this article, we’ll cover the main differences between these commonly used materials.

We also have this handy Youtube explainer video that covers the differences between PLA and ABS filaments.

What are PLA and ABS filaments?

PLA (Polylactic Acid) is a thermoplastic derived from renewable sources such as cornstarch or sugarcane. Biodegradable under the right conditions, PLA is one of the most popular bioplastics and is perfect for a variety of applications ranging from plastic cups to medical implants. It’s easy to print with and has a higher stiffness than ABS and materials like nylon. While PLA is stronger than ABS and nylon, it’s not very heat or chemical resistant. 

ABS (Acrylonitrile Butadiene Styrene) is another common thermoplastic, also popular in the injection molding industry. ABS has superior mechanical properties to PLA, as well as being more durable and lighter, though it’s harder to print with. This material is better able to deflect heat than PLA and nylon, but it’s absolutely not completely heat resistant. Prevalent applications of ABS include LEGO bricks, electronic housings and automotive bumper parts.

What’s the difference between PLA and ABS? 

PLA and ABS differ in several ways, including their unique tensile strength, density and ideal applications. The table below compares the key material properties of PLA and ABS filaments.

What is the part accuracy of PLA and ABS?

In general, the tolerances and accuracy of FDM printed components depend on printer calibration and model complexity. However, you can use PLA and ABS to create dimensionally accurate parts with printing details of 0.8 mm and minimum features of 1.2 mm. For connecting or interlocking parts, we recommend a tolerance of 0.5 mm and a minimum wall thickness of 1-2 mm. This will ensure that your part has adequate strength across all wall elements. 

Thanks to its lower printing temperature, PLA is easier to print with and less likely to warp (when properly cooled). You can use PLA to print sharper corners and finer features than with ABS.

How strong are PLA and ABS parts?

PLA and ABS have similar tensile strengths, making them solid options for many prototyping applications. Designers and engineers often prefer ABS due to its improved ductility over PLA. ABS has higher flexural strength and better elongation before breaking than PLA, which means that ABS can also be used for end-use applications. PLA, on the other hand, is more popular for rapid prototyping when the form is more critical than the function.

Overall, PLA is a good option for your custom parts if you don’t plan on putting them under a lot of physical stress (or UV radiation and high temperatures). ABS is more fitting for industrial applications and can weather physical strain better than PLA.

How fast can you print with PLA and ABS?

Both PLA and ABS print at nearly identical speeds. This means that you don’t have to change speed settings on your FDM machines when switching between materials. For PLA, printing at 60 mm/s is pretty standard, though some operators have printed at over 150 mm/s, so the standard speed is by no means a limit. You can also print ABS at the same speed, but between 40-60 mm/s is a bit more accurate for this material.

Surface finishes and post-processing for PLA and ABS

Whether you produce parts using PLA or ABS, FDM-printed components will always have visible layers. Using PLA often results in a glossier finish, while ABS typically prints in a matte finish. To smooth an ABS-printed part and give it a glossy finish, you can use acetone in post-processing. Sanding and additional machining are viable post-processing options for parts printed in ABS. You can also sand and machine PLA, though greater care is required. 

If aesthetic quality is critical, then we recommend using SLA 3D printing to produce your custom parts. 

How heat resistant are PLA and ABS?

For applications requiring higher temperatures, ABS (glass transition temperature of 105°C) is preferable over PLA (glass transition temperature of 60°C). PLA can rapidly lose its structural integrity and can begin to droop and deform as it approaches 60°C, especially if it's supporting a heavier load. 

Are PLA and ABs biodegradable?

PLA is stable in general atmospheric conditions, though it will biodegrade within 50 days in industrial composters and 48 months in water. While ABS is not biodegradable, you can recycle it. This being the case, manufacturers tend to use PLA to produce items related to food service, though we absolutely recommend you get safety confirmation from filament manufacturers.