ABS vs. ASA 3D Printer Filament: Understanding the Differences for Better 3D Printing

In the rapidly changing world of 3D printing, your choice of 3D printer filament type can significantly impact the quality, durability, and utility of printed objects.

There really is no “best” filament; there is just the right filament for different types of jobs, with different types of requirements. 

While in the past, most people preferred to stick to Polylactic Acid (PLA) or Polyethylene Terephthalate Glycol-modified (PETG), the increasing popularity of enclosed 3D Printers has led to an increase in demand and interest for other materials, previously thought to be very difficult to print on open-format 3D printers.

These include ABS (Acrylonitrile Butadiene Styrene) and ASA (Acrylonitrile Styrene Acrylate). While these two types of 3D printer filaments share significant similarities, their unique properties make them suitable for entirely different applications.

In this article, we’ll explore some of the distinctions between ABS and ASA filaments, to help you make informed decisions for your next 3D printed project.

ABS: The Established Player

Though often considered “old school” or difficult to print in the era of PLA, ABS has long been a favorite in the 3D printing community. Common in injection molding and traditional manufacturing, this polymer is known for its strength, flexibility, and high-temperature resistance.

It is a petroleum-based thermoplastic that is durable and relatively inexpensive, making it an attractive option for a wide range of applications. ABS is particularly noted for its ability to be easily sanded or vapor-smoothed post-printing, which is ideal for projects requiring smooth finishes or detailed work.

Pros:

• Durability and Strength: ABS is known for its toughness, making it suitable for parts that need to withstand mechanical stress or wear and tear.
• Thermal Resistance: With a relatively high melting point, higher than PETG, but lower than, say, Nylon, ABS can withstand temperatures without deforming, making it ideal for objects that might be exposed to heat.
• Post-Processing Ease: It can be easily sanded, acetone smoothed, and painted, allowing for high-quality finishes.

Cons:

• Warpage: ABS has a tendency to warp or shrink during cooling, which can lead to print deformities if not managed correctly.
• Ventilation Needs: It noxious emits fumes during printing, necessitating good ventilation for safe use, or, better yet, the use of a carbon pellet filter such as the Nevermore or Bento Box.
• Printer Requirements: ABS requires a heated bed and an enclosed print area to manage its tendency to warp.

ASA: The Rising Contender

ASA is the better choice for anything that’s going to be in the sun!

You may not have heard of ASA, but it has been gaining popularity as a viable alternative to ABS, especially in outdoor applications. It is a copolymer of ABS and possesses many of the strengths of ABS… but with a number of valuable benefits, particularly in terms of UV resistance and weatherability.

ASA's ability to withstand prolonged exposure to sunlight and the elements without losing color or physical properties makes it a preferred choice for outdoor projects. Though most people don’t realize that it is also more impact-resistant, stronger, and heat-resistant than ABS.

Pros:

• UV Resistance: ASA is highly resistant to UV radiation, which prevents discoloration and material degradation in sunlight.
• Printability: ASA boasts lower warping and fewer fumes than ABS, making it easier to print in some ways (more on that in the cons section!)
• Weather Resistance: It is more resistant to water, chemicals, and environmental factors than ABS.
• Aesthetic Finish: ASA prints have a higher aesthetic quality with less visible layer lines, and it's available in a wide range of colors.
• Strength: ASA does have some minor strength improvements over ABS, particularly in it’s impact resistance (though still inferior to something like Nylon)

Cons:

• Printability: While ABS is easier to print in some ways, it can be more challenging to print in other ways, due to its slightly higher melting point and the fact that it does not adhere as nicely to the print surface as ABS
• Cost: ASA is generally more expensive than ABS, which can be a consideration for large-scale projects or budget-conscious users. Hopefully, this will change in the future as this material reaches economies of scale
• Ventilation: Though less noxious than ABS, ASA definitely still emits fumes when printed, requiring good ventilation.

Comparing ABS and ASA: Use Case Considerations

When deciding between ABS and ASA, it's essential to consider the specific requirements of the project. ABS is excellent for indoor items, particularly those that require strength and flexibility, such as functional prototypes, gears, and automotive components.

On the other hand, ASA's UV and weather resistance make it ideal for outdoor applications, including garden equipment, automotive exterior parts, or signage that requires long-term color stability and material integrity.

Engineers and Material Scientists at Stratasys have done extensive research and found that ASA boasts slightly higher tensile strength, inter-layer adhesion, and IZOD impact resistance than ABS.

Printing Considerations

Both ABS and ASA require careful temperature management during printing. A heated bed is crucial to prevent warping, and an enclosed printer is recommended to maintain a stable temperature. For ABS, the typical print temperature ranges from 220°C to 250°C, while ASA prints at slightly higher temperatures, usually around 235°C to 260°C. For bed temperatures, ABS can adhere nicely to many surfaces, without glue stick, at 80-100°C. ASA, on the other hand, does best at 90-110°C - and may still require the use of glue stick or hair spray.

Health and Safety

While ASA is noted for having fewer observable fumes, the emissions produced by both ABS and ASA during printing can be harmful if inhaled in large quantities. It's essential to use these materials in well-ventilated areas or with a filtration system. If using carbon pellets, ensure that you are changing them out regularly, as they can quickly become saturated.

Conclusion

In summary, both ABS and ASA filaments offer unique advantages for 3D printing, with ABS being the go-to for strength and post-processing ease, and ASA excelling in outdoor durability, warping resistance, and UV resistance.

The choice between the two ultimately hinges on the specific requirements of the printing project, taking into account factors like environmental exposure, required durability, budget, and finish quality. With their distinct properties, ABS and ASA continue to be valuable assets in the toolbox of 3D printing enthusiasts and professionals alike.

About The Author:

Jonathan Levi is a YouTuber and 3D Printing expert. In 2022, he founded The Next Layer and its YouTube channel, where he posts weekly videos about various interesting 3D printing projects and products.