Brittle PLA is a very common problem in 3D printing and can be fixed quite easily. In this post, we’ll look at why PLA goes brittle and what are the ways you can solve this issue.
Why does PLA become brittle?
PLA can become brittle due to one or a combination of three causes: moisture, mechanical stress from being coiled up, and being low quality. Removing these factors can help prevent PLA filament from snapping at the wrong time.
1. Too much moisture
PLA is very hygroscopic, which means it absorbs moisture very easily. Any atmospheric moisture will be absorbed over time and this reduces the overall integrity of the filament.
That’s why manufacturers ship PLA vacuum sealed in plastic and with a packet of desiccant.
2. Mechanical stress
PLA filaments ship wrapped around a spool. When manufacturers make PLA, it is pulled into a thread and wrapped directly around the spool.
As a result, the PLA assumes a coiled shape. Trying to hold the filament straight for too long can put a lot of stress on the filament and cause it to snap.
3. Poor quality
If you’ve been 3D printing for a while, you’ll know that all filaments are not made equal. Filaments made by reputed brands tend to perform much better than other cheaper filaments.
That’s because well-known brands usually have much more robust quality control, and a reputation they need to maintain. Poorer quality filaments can have unknown additives or generally poor manufacturing standards that can make them brittle and snap very easily.
So which factor is it?
Usually, a single factor is not responsible for making filament brittle. A combination of the factors makes the problem worse. For example, moisture can add to mechanical stress, and lower quality filaments tend to fare worse with lower levels of moisture than other filaments that have more tolerance for moisture.
How to fix brittle PLA
The fix for brittle PLA largely involves removing moisture. There is one solution for mechanical stress, but it’s a stopgap solution at best.
Store your filament properly
The most important thing you can do to fix(prevent) brittle PLA is to store it properly. This means keeping it away from moisture and keeping it in an airtight container.
As an extra measure, you should also throw in a few packets of desiccant to make sure any renegade moisture is also sucked out of the air left in the container.
You’ll notice that manufacturers ship their filaments vacuum-sealed with desiccant. Once you break the seal, it’s up to you to store it properly.
This is especially important if you live in an are that has a humid climate.
Dry your filament out
If you’ve left your filament out for a while already, chances are it has already absorbed moisture. The best thing you can do now is to try to remove some of that moisture.
You can do this by making a DIY filament drier using the same method as above: store each roll of filament in an individual airtight container and add a generous amount of desiccant.
Then leave it in there for a couple of days(depending on how bad the filament is) and it should have lost some of the moisture.
You can also invest in a filament drier, which gently heats the filament to help force the moisture out.
We’ve made a list of the best filament dryers here.
Make the filament less taut
Changing the position of your filament roll can also help. If the roll is positioned in a way that it is very taut when going from the roll into the extruder, it’s coming under unnecessary tension.
By adjusting the position of the spool, you can let the filament be a little looser as it goes into the extruder. This will loosen the tension and prevent any unnecessary breaks.
Invest in a dehumidifier
For those of us living in very humid areas and running 3D printing farms, the best solution may just be to get a dehumidifier for your 3D printing room.
Dehumidifiers are very effective at sucking moisture out of the air, and if you have multiple rolls of filament and need to store them all outside, dehumidifying the whole room is the way to go.
Of course, this is a rather expensive solution for a hobbyist, but if you’re looking to scale up, then it may be worth investing in one.
Dehumidifiers do require a small amount of maintenance: you’ll need to empty the tank every now and then as it fills up.
Get better filament
Finally, the best way to avoid brittle PLA prints is to invest in good quality filament. Even the best filament in the world will not be immune from moisture, but it will generally perform much better than lower quality stuff.
This is simply because reputed manufacturers have very strict manufacturing standards and you can trust their products to always be good.
Cheaper filaments end up costing more in the long run thanks to failed prints!
See a list of the best PLA filament here.
Brittle PLA is a really annoying thing to deal with in 3D printing, but it has a few solutions that you can try. On the whole, buying good filament and storing it properly will help prevent any brittle PLA issues you may run into.