Curling or warping is a common 3D print phenomenon that negatively impacts the quality of your prints.
When it happens, the edges of the layers curl up, compromising adhesion.
The most common reasons for 3D print curling are uneven cooling, poor bed adhesion, inadequate nozzle or bed temperature, and poor filament quality. Moisture and the print speed can also cause warping. To prevent the problem, you must identify the cause and correct it.
7 Common Causes Of 3D Print Curling
An uneven or too fast cooling are two of the main reasons for filament curling up, but not the only ones. Here are the most common culprits.
1. Uneven Cooling
Cooling issues are the most common causes of warping, and one of them is uneven cooling.
This problem is more frequent in large prints, but it can happen in smaller pieces as well. Uneven cooling is often the result of printing in an open room rather than an enclosure.
In such circumstances, gusts of air can hit the model and cool one side more than the other. A lower room temperature can also cause a quick cooling, which can lead to shrinkage in curling – especially in filaments prone to shrinkage, such as polyethylene.
However, slow cooling can also be undesirable. In this case, the filament has time to shrink and deform before its solid form keeps it in the desired shape.
An easy solution is to use a 3D printer enclosure and set the cooling fan at the speed required by the material.
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2. Wrong Nozzle Temperature
A printing temperature set too low or too high can be responsible for your object curling at the edges, but also filament curling around the nozzle’s tip and clogging it.
Each filament comes with recommended temperature settings that you must respect. These ranges give you enough wiggle room so that you can find the perfect temperature for a given material based on the 3D printer you’re using. Ranges may slightly differ from brand to brand.
Setting the temperature lower than instructed could be tempting, especially if you’re printing with a material prone to stringing.
However, if the material is too viscous when extruded, it won’t adhere properly to the bed. Layer adhesion can also be problematic, and you might find yourself dealing with both warping and delamination.
If the nozzle temperature is too high, the filament becomes too liquid. Hence, it will need a longer time to cool down and solidify after extrusion. In this time, it can curl due to uneven cooling or shrinking.
3. Wrong Bed Temperature
Just like the nozzle temperature, the bed temperature can make or break the deal.
An adequate bed temperature is necessary for all filaments that require a heated bed. These materials won’t stick to the bed otherwise, and the corners of each layer are very likely to curl up.
4. Poor Bed Adhesion
Besides bed temperature, there are other bed-related factors that can cause adhesion issues and 3D print curling up.
A dirty bed and printing on the wrong bed surface are two of the most common causes.
To improve bed adhesion, you should make it a rule to wipe the bed clean after each print. Use isopropyl alcohol or another type of solvent to remove all filament residues. If they remain stuck to the bed, they can cause leveling issues with consequent curling.
PETG, ABS, PLA, TPU, and nylon are generally compatible with all build surfaces.
HDPE, however, requires a polypropylene build plate. ASA is another tricky filament best printed on G10, which is a lesser-known plastic material similar in structure with carbon fiber.
Bed leveling issues can also lead to warping.
For this reason, it is crucial to calibrate the bed before each print. Marlin’s Auto Bed Leveling function can help in this endeavor.
5. Too Fast Print Speed
Warping is also common when you’re printing too fast. Setting a lower speed is crucial, especially for the first layer.
While you’re at it, you should also set the right distance between the build plate and nozzle. The optimal distance is the layer height.
If you have to alter the bed position after calibrating – for instance, to add a glass pane – you can adjust the nozzle height without having to recalibrate the bed using Cura’s Z offset.
The table below compares the ideal printing speed for the three most popular filament types*:
|Material||Ideal Speed for First Layer||Ideal Printing Speed|
*The values in the table are averages based on different filament brands, when printed with different machines. Actual numbers may vary.
6. Wet Filament
Another common culprit when warping is involved is wet filament.
Not all filament types are affected by this issue, but if you’re printing with a hygroscopic material – such as PETG, ABS, or PLA – you should dry the filament before printing with it.
That’s because water inside the filament mixes with the melted plastic as it’s heated for extrusion and causes a variety of structural and aesthetic issues.
7. Low-Quality Filament
Lastly, you should only use quality filament.
Poor quality materials may have adhesion issues regardless of the parameters and adhesion enhancers you use. As you can expect, this leads to the material curling up.
Diagnosing 3D Print Curling Up
Warping has many potential culprits, but you can map curling up scenarios to 3D printer issues for a quick diagnosis.
Nozzle overheating is often responsible for 3D printing edges curling up.
A too fast printing process is another potential cause.
When the print curls up off bed, you might want to check the bed temperature and cooling fan settings.
Uneven cooling could also be the cause, which could be triggered by an incorrect printer location.
First layer warping is almost always caused by bed adhesion issues.
Poor bed adhesion can be caused by a dirty bed, improper printing surface, or an uneven bed.
How To Prevent 3D Print From Curling
Once you identify the most likely cause, these tips should help you fix the warping issues.
Optimize Printing Temperature
Setting the right parameters in your slicer is key to preventing warping. Each filament comes with temperature recommendations for both nozzle and build plate, and you should respect them.
The table below compares the ideal printing temperatures for the three most common filaments:
|Filament Type||Nozzle Temperature||Bed Temperature|
|PETG||230°C – 245°C||80°C – 100°C|
|PLA||190°C – 220°C||60°C – 70°C|
|ABS||220°C – 250°C||95°C – 110°C|
Tip: To find the sweet spot for your 3D printer, start from one end of the range and decrease or increase the temperature by 5°C at a time, until warping is no longer an issue.
Use a Printer Enclosure
Uneven cooling is the main cause of warping, and one of the most common causes of uneven cooling is a room temperature that fluctuates. This can happen due to an open window or someone opening a closed door.
To prevent these issues, it is best to use a printer enclosure.
Avoid Room Temperature Fluctuations
If you can’t afford an enclosure, you should do everything that you can to ensure a constant temperature in your room.
Ideally, you should set a higher room temperature to minimize nozzle and bed heat loss. A higher room temperature can also reduce the cooling speed.
Place the printer in a spot away from doors and windows. If possible, choose a windowless room, or avoid opening the window while you’re printing.
Turn Off the Cooling Fan
For difficult materials prone to curling, such as ABS, you may want to turn off the cooling fan completely.
This can slow down the cooling process enough to avoid shrinking.
Print More Slowly
In addition to turning off the cooling fan, reducing the printing speed will also help. This is especially true for the first layer, which shouldn’t be printed at a speed faster than 30mm/s.
For all subsequent layers, use the lower threshold of the speed range, which generally is around 60mm/second.
Add a Raft
Another trick to deal with difficult materials is using rafts and brims.
Adhesion is typically better compared to a bare bed, reducing first layer curling.
Improve Bed Adhesion
There are various ways to improve bed adhesion, but the most important one is to keep the bed clean and leveled.
Adhesion enhancers include blue painter’s tape, hairspray, and glue stick. An additional build plate, such as a PEI sheet or tempered glass pane, could also help for some filaments.
Optimize Layer Thickness
Optimizing the layer thickness or height can also help mitigate curling up.
Ideally, the layer thickness should not exceed 80% of the nozzle diameter.
Pay Attention to Filament Quality
Another essential thing is to make sure you’re using premium quality filament.
Hatchbox, Prusament, and eSun are some of the brands that won’t disappoint you.
What happens if filament is too hot?
Too hot filament needs a longer time to cool down. As it remains flexible, the model edges can curl up due to shrinking or uneven cooling.
Too hot filament is also more prone to stringing.
How hot can PLA get before warping?
You can heat PLA filament to around 220°C without issues, but anything above this threshold can cause warping.
Also note that some filament brands or colors may require cooler temperatures and can warp before heating to 220°C.
Cooling and bed adhesion problems are the main reasons why 3D prints curl up. An improper nozzle temperature and wet filament could also affect printing quality and lead to warping.
To prevent this issue, keep the bed clean and level it before each print. Make sure the slicer settings are right and use an adhesion enhancer or rafts when printing with particularly challenging materials.