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Though PLA and ABS are said to be the most used types of materials in 3D printing,
most of us take PLA as our go-to filament.
It's cheap, easy to print with, also available in so many colors,
and creates strong prints with nice look.
Sounds perfect.
But, if so, why do we need ABS?
That's because, like Snapmaker users said, LEGO is made from ABS.
That's all you really need to know.
Well. You have to admit that ABS is in some ways better than PLA. For one, durability.
PLA's stiffness and high static strength make it quite brittle.
It snaps off when bent to a certain angle.
By contrast, ABS merely distorts instead of breaking, due to its flexibility.
That's why ABS is widely used to print something that might be worn,
dropped or bent frequently, such as door catches, clips and hooks.
Now, it's obvious why building brick toys like LEGO are made from ABS, isn't it?
The second advantage of ABS is its high glass transition temperature.
It's about 105℃ for ABS, while only 60℃ for PLA.
To demonstrate this, let's print two strips with PLA and ABS,
and put them into an oven.
Set the temperature at 100℃, and see what happens.
We can see that PLA softens gradually as the temperature increases,
while ABS has no obvious change.
That means ABS can be used in a hotter environment or as mechanical structures.
Examples include automobile parts, machine enclosure, and some outdoor applications.
Though ABS is better for practical uses, it's trickier to print with.
You can follow these rules for a better printing experience:
First, ABS produces a kind of VOCs called Styrene when heated,
which is smelly and harmful. So, keep good ventilation during printing.
You can use a dedicated air purifier,
or expel the fume outside with an enclosure equipped with exhaust fan.
Second, ABS must be printed at a higher temperature than PLA.
You'll find a recommended temperature on most filament spools and boxes.
If not, try setting it between 210℃ and 250℃.
Also, use a heated bed, and set the temperature at 80℃-110℃.
When setting the parameters in Snapmaker Luban,
you can go to [Customize] > [Heated Bed Adhesion Type],
and add Brim or Raft to your print.
Both options will create additional surface contact between the print and the bed
to help with first layer adhesion.
If you can do all of the above,
you are almost guaranteed a nice print with ABS.
But still, you might have quality issues with your project.
Here, we'll talk about 2 common issues with ABS printing, and how to fix them.
The most common problem is warping or cracking caused by temperature change.
When the filament is extruded out of the nozzle, it starts to cool, solidify and thus contract.
The ABS print is likely to over-shrink and warp if the bottom layers cool too fast,
and crack along layer lines when it comes to the middle part.
To fix this problem, you can try as follows: first, level the bed properly.
This applies to all types of filament.
Second, as is mentioned above, use an enclosure.
Besides exhausting, the enclosure also works as an insulation cover
that help maintain warmth around the nozzle,
so that the extruded filament will not contract too much due to temperature variation.
Third, finetune the temperature and speed parameters to achieve a better first layer adhesion.
This includes turning up the Bed Temperature,
Initial Layer Printing Temperature and Initial Layer Line Width,
as well as turning down the Initial Layer Print Speed and Initial Layer Height.
Fourth, apply some 3D printing glue or blue tape to your heated bed,
and then print on them. They can help with adhesion, too.
The last one is sort of unconventional – changing the G-code to turn off the cooling fan
if necessary.
Export the G-code, open it with Notepad,
find and delete the line of "M106 S255".
Then, save the file, and load it to the machine.
By changing the code, we can minimize the air flow around the nozzle,
and let the filament cool more slowly.
The other problem with ABS printing is its tolerance to vertical overhang and bridging structure.
ABS is more likely to curl and sag as the overhang angle or bridge length increases.
At 50°, PLA looks alright, while ABS has some flaws at the edge.
When it reaches 75°, both of them have obvious saggings, but PLA is apparently better.
And at the same length, ABS bridges have more saggings or breaking-offs than PLA.
One way to improve ABS overhang is lowering the print speed and the layer height.
You can also set a proper Support Overhang Angle,
so that parts beyond that angle can be supported.
For most ABS filament, the angle can be up to 45°.
Also, always choose the right filament.
When durability and heat resistance are not that important,
you might as well print overhangs or bridges with PLA.
To sum up, ABS is more demanding on the environment and the printing skills.
It can be a little more difficult to print with than PLA.
But on the plus side, ABS is more flexible and heat resistant,
while having enough strength, making it a really handy material.
With a little more time and patience, you can definitely print pretty well with ABS!
Have fun making!