PLA vs ABS: Which 3D printer filament should you use? We simply explain the differences and the fields of application of ABS and PLA Filament.
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When it comes to desktop 3D printing, the two most common filament types are PLA and ABS. Both are thermoplastics, meaning they become malleable when heated. In this way, you can use them while hot to create any shapes you want, and then let them cool to preserve those shapes forever! (Probably.)
Yet, despite the ways in which these filaments are similar, they also have a great many differences.
Polylactic Acid (PLA) is a biodegradable thermoplastic, made from renewable resources like corn starch or sugarcane. Outside of 3D printing, it’s typically used in medical implants, food packaging, and disposable tableware. The main benefit of PLA is that it’s easy to print.
Acrylonitrile butadiene styrene (ABS) is an oil-based thermoplastic, commonly found in (DWV) pipe systems, automotive trim, protective headgear, and toys (like Lego!). Objects printed with ABS boast slightly higher strength, flexibility, and durabilitythan those made of PLA, at the cost of a slightly more complicated print process (complete with nasty fumes!).
So when should I use PLA, and when should I use ABS? This article aims to answer exactly that question, and in the meantime provide a fair amount of background information on both materials.
When considering whether or not to use a particular filament, the relevant information falls under one of two categories: On the one hand, you probably want to know, How easy is it to print with? And on the other hand, What will the final product look like?
With these two questions in mind, the following guide provides a detailed comparison between PLA and ABS, in particular giving
“It is better to create than to learn! Creating is the essence of life.” – Julius Caesar (William Shakespeare)
As was mentioned in the nutshell, it is generally easier to print with PLA than with ABS, thus PLA filament is a natural choice for beginners. It melts at a lower temperature, tends not to warp, and smells like candy! That’s not the end of the story, though. Keep reading to learn just how easy it is to print with both materials…
Plastic melts when you heat it, right? Well, yeah, but not right away. In reality the process is a little more complicated, but can be “boiled” down to these three stages:
Why is all of this so important? Because the points between the stages, the glass transition and melting temperatures, directly influence a filament’s print bed and printing temperatures. Basically, in order not to alter the print process, the print bed must be kept well below the glass transition temperature. And of course, in order to ensure that the filament is a liquid, it must be printed well above its melting temperature.
With the science out of the way, take a look at the following table. It presents not only the glass transition and melting temperatures of both materials, but also our recommended print bed and printing temperatures.
*As a purely amorphous substance, ABS has no true melting temperature (but always liquifies well before the recommended printing temperature).
The above table begins to show us why PLA is easier to print with than ABS. Thanks to its low glass transition and melting temperatures, printing with PLA filament generally requires less heat. In fact, a heated print bed isn’t even necessary! (Although it certainly helps.)
The one printing difficulty PLA presents over ABS is that it can sometimes clog or jam the printer nozzle. This occurs because PLA expands and becomes sticky when it melts. Achieving a good flow is a simple matter of fine-tuning the print settings, either through following the filament manufacturer’s instructions to the tee, or by playing around. (After all, we are having fun, aren’t we?)
ABS, on the other hand, tends to flow quite beautifully from the nozzle, likely due to its much higher print temperature.
Time for PLA to shine once again! With no special sensitivities to temperature, it requires neither a heating bed nor an enclosure. (Although, once again, they help.)
ABS is more sensitive to changes in temperature than PLA, resulting in cracking and warping if it cools too quickly. This is why a heated print bed it is absolutely necessary when printing with ABS. We also recommend using a full enclosure around the print area.
Both materials present some minor problems with first layer adhesion. In other words, they sometimes stick to the print bed. The three most common solutions involve covering the print bed with tape, glue, or hairspray. For tape, we recommend using Kapton Tape (a polyimide film with a silicone adhesive), but masking tape also works fairly well.
Ever the favourite child (in the context of printing), PLA gives off little to no smell when heated, and some even claim to have picked up on fruity or candy-like aromas…
ABS stinks. And the fumes are intense, in some cases inducing headaches! Whenever possible, print in an open (but isolated) area with proper ventilation.
Both materials are hygroscopic, meaning they attract and absorb moisture from the air. This is a negative attribute because, as levels of hydration rise, the print process degrades and print quality declines. Bubbling, spurting, and even clogging can occur at the nozzle, while discoloration and poor detailing can appear in the final product.
The bottom line: Don’t expose your filament to air (and therefore water) for long periods of time.
And that’s easily done! Simply store your filament rolls in sealed containers when not using them, and place those in cool, dry places. As an extra precaution, filament manufacturers often recommend using up rolls as soon as possible.
“I’ve always believed that if you put in the work, the results will come.” – Michael Jordan
PLA filament may be better to print with, but is it the better material for your print? Referring back to the nutshell, the quick answer is no, as ABS is not only stronger, but more flexible and durable as well. For the long answer, well, you’ll just have to stick around…
ABS – our new prodigy – owes its toughness to polybutadiene, a synthetic rubber with a high resistance to wear. To give you an idea of just how tough this rubber is, 70% of the all polybutadiene goes into the production of tires. In ABS filament, this toughness is reflected in its superior strength and high impact resistance. (Remember that it’s used in protective headgear and automotive trim!) And while not the most flexible of materials, ABS still outshines PLA, as it tends to distort, then bend, before finally breaking.
About the only thing PLA can brag about, with respect to mechanics, is a higher surface hardness. Otherwise, it exhibits only decent strength, and is brittle, preferring to break rather than bend.
In general, ABS is more durable than PLA because of its high resistance to heat. Remember that plastic no-man’s-land? That temperature range where thermoplastics are more-or-less useless? Well, thanks to a comparatively high glass transition temperature, it takes a lot more heat for ABS to reach that point than for PLA. That’s what makes it better suited for objects that remain in the sun. Because nobody wants to see a droopy-nosed garden gnome.
With respect to the other elements, ABS performs no better than PLA. When exposed to UV rays and moisture, both materials degrade over time.
One nice characteristic of PLA, as mentioned in the nutshell, is that it’s biodegradable. Don’t expect it to degrade in your backyard composter (it needs some heat), but feel free to add it to the compost collected by your city. ABS, on the other hand, is only recyclable.
If you’re willing to put in that little bit of extra effort to turn your print from something pretty into something beautiful, both ABS and PLA are pretty tolerant, although ABS once again comes out on top.
While both materials can be cut, filed, sanded, painted (with acrylic), and glued, it’s recommended to use primer before painting PLA, and gluing it may not always work. Additionally, only ABS can be treated with acetone (i.e. nail polish remover) to get that smooth and shiny surface, because only ABS is acetone-soluble. On the other hand, PLA is slightly more forgiving of complex design features, despite both materials being able to handle 100-micron layer heights.
The possibilities for filing, sanding, or acetone treatment are especially important to keep in mind if you’re using rafts, as they don’t always separate nicely from the rest of the print, leaving behind undesirable surfaces which you’ll probably want to clean up.
Filament for both materials come in a wide range of colors – there’s even translucent filament!
Special “exotic” filament types also exists, as blends of either ABS or PLA with other materials. The most popular varieties include wood, metal, and glow-in-the-dark. For more information on these exotic filament types, check out our 3D Printer Filament Guide.
By the way, if you’re looking for a slightly more flexible and durable filament than either PLA or ABS, take a look at PETG.
Filament for both materials have more-or-less identical pricing, with exotic filaments being a little more expensive, as you might expect.
PLA is the most widely used filament in 3D printing, not because it’s the “best” material, but because it’s easy to print with. And after all, why make life harder than it needs to be? With that idea in mind, we recommend using this 3D printer filament for anything that doesn’t have specific requirements for mechanical properties, durability, or degradability.
Remember to avoid using PLA filament for items that might be bent, twisted, or dropped repeatedly, such as phone cases, high-wear toys, or tool handles. You should also avoid using it with items which need to withstand higher temperatures, like if you want to place them in direct sunlight, a car, or the dishwasher. For all other applications, this filament makes for a good overall choice in filament. Common prints include models, low-wear toys, prototype parts, and containers.
ABS filament is better suited for items that are frequently handled, dropped, or heated. It can be used for mechanical parts, especially if they are subjected to stress or must interlock with other parts. Examples of prints which take advantage of the qualities of this filament include phone cases, high-wear toys, tool handles, automotive trim components, and electrical enclosures.
Header image from Filamentworld.
License: The text of "PLA vs ABS: Filaments for 3D Printing Explained & Compared" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.