ABS (Acrylonitrile Butadiene Styrene) is a common filament used in 3D printing that belongs to a family of thermoplastics, which means it can be reused and recycled. As a thermoplastic, it is typically solid when cold but can be heated until soft, such as in a 3D printer. However, 3D printing with ABS is a bit more complex than meets the eye due to its unique properties.
ABS starts to soften at a temperature of 105 °C (221 °F), which is its glass transition temperature. At this point, it will soften and become pliable enough to be extruded through a 3D printer nozzle. However, ABS does not have a set melting temperature, and each polymer blend will melt differently.
This article will give you all the details about ABS’s thermal properties in the simplest terms possible to understand how this filament works and how to print with it. By the end of this article, you’ll have a polymer scientist’s perspective on ABS, and hopefully, you’ll know just how hot you can get it before it starts to deteriorate.
Does ABS Melt?
If you’re like me, you’ve probably never really thought much about what happens to plastics and polymers as they get hot.
To the naked eye, hot material is either solid, soft, or burnt to a crisp. However, as with almost anything, heat exists on a spectrum, and melting comes in many shapes, forms, and textures.
ABS does melt, but it does not have a set melting point. Because ABS is an amorphous solid, it has a glass transition temperature of 105 °C (221 °F), which is when it starts to develop a pliable, rubbery texture. As it gets hotter, it slowly and gradually turns into a liquid.
Understanding How ABS Melts
Amorphous solids, by definition, do not have a set melting point. Instead, they have a set glass transition temperature.
Glass transition temperatures are less focussed on the simple melting process and instead indicate when an amorphous solid loses its glassy, hard texture and develops a rubbery, soft texture.
Melting, specifically, is when a solid turns into a liquid. However, the glass transition temperature, which only applies to amorphous solids, is a heat level at which a material becomes soft and pliable before it melts entirely.
So, this could be seen as the start of the melting process.
ABS Melting vs. Softening
To put this in simple terms, let’s compare ABS to an ice cube.
Ice cubes are not amorphous solids, and they do melt. So, when an ice cube reaches its melting point, it becomes liquid.
However, ABS doesn’t turn into a liquid when it reaches its glass transition temperature. Instead, it develops a rubbery, sticky consistency pliable enough to print with.
I like to think of the glass transition temperatures in terms of spaghetti noodles.
When noodles are dry, they are solid. When you heat them in boiling water, they become rubbery, chewy, and soft, just like ABS when you heat it to its glass transition temperature.
Cook the noodles for too long, and they’ll dissolve in the water, turning back into the flour they’re made of.
ABS goes through a similar process.
ABS Melting Depends on the Polymer Blend
As you heat the ABS more and more, it will gradually melt and dissolve.
However, the temperature it melts at and the amount of time it takes to liquefy will depend on any other chemicals inside the polymer blend and the environmental conditions.
Thus, every ABS filament will respond to heat quite differently.
So, no one can say precisely when ABS will liquefy or melt. Nevertheless, we can always predict when it will get mushy and sticky enough to use in a 3D printer or injection mold.
For more details about ABS, check out this YouTube video from a fellow 3D printing enthusiast, Thomas Sanladerer:
What Temperature Should I Print ABS Filament At?
ABS filament should be printed at a temperature between 240 °C and 270 °C (464 ° F to 518 °F). However, every filament is different, so you should use the recommended temperature from the manufacturer’s instructions. It’s also important to run test prints when using new filament.
As you might know from the ideal printing temperature, ABS is exceptionally resistant to heat. Unfortunately, not all printers can get that hot, so you’ll need to check your printer’s user manual before you attempt to 3D print with ABS filament.
If you’re printing ABS for the first time, look at your filament spool for the recommended print temperature, and go for the temperature setting that falls directly between the provided range.
Should the filament clog the nozzle, raise the heat by about 5 °C (9 °F). However, if your filament starts to string, lower the temperature by 5 °C (9 °F).
Continue to make adjustments until you find the sweet spot, then write that temperature on your filament spool. That way, you can easily find the ideal temperature for each filament when you use it again.
Is ABS Food-Safe?
I’ve heard this question repeatedly: if ABS resists melting, does that mean it is safe to use as a food or water container?
The big answer is: absolutely not.
ABS is not food safe, and you should never eat food out of it. ABS leaches out harmful gasses and particles that can poison you, especially when hot. So never use it in a microwave, oven, or any food preparation.
In general, any food-safe filament out there has its risks. Polymers are complicated, and even if one of them resists melting, that doesn’t mean that it doesn’t have toxic ingredients that may come loose during the heating process.
That said, ABS is a popular food-safe material at room temperature or colder. In fact, your refrigerator lining is probably made of ABS, and Legos are made of it, too. However, when it’s hot (I speak from experience), it develops a terrible chemical smell that will make you cough.
Studies confirm it, too. ABS, when heated, deposits chemicals into the air that tends to make their way into our lungs. Once they do, there’s no way back.
So, always ensure proper ventilation when printing with ABS, never use it to hold water or food, and don’t heat it after printing.
Also, please do not use plastic for food prep or eating unless you are sure it is food-safe. Some companies will try to get the better of the deal by miseducating you, but if you learn about the thermal properties of any plastic, you will be able to tell when something is food-safe or not.
Final Thoughts
ABS is a great filament as long as you understand what you are getting into.
As an amorphous solid, it has a glass transition temperature of 105 °C (221 °F), when it gets soft enough to print with. However, chemical additives and ratios in the filament may interfere with this ideal “melting” temperature.
Regardless of how durable and heat-resistant this filament is, it is not safe to use as a food or liquid container. So, always exercise caution when using ABS and use proper ventilation every time you print with it.