# Curling of Layers and Angles
This problem can mimic what looks like warping, but rather than the part warping\
off of the build plate, the individual layers seem to be warping upward, which we refer to as curling. You will see that the solutions to this problem are nearly the exact opposite of the ones given in the “[Warping](https://us.polymaker.com/blogs/3d-printing-tips/warping)” page, since this curling issue doesn’t actually have anything to do with warping.
### **Turn on Active Cooling Fan**
Curling issues most frequently occur when printing PLA without an active cooling fan or with insufficient fan speed. Optimal PLA printing typically requires activating the cooling fan at 100% capacity following the completion of the first layer.
**Visual Evidence**\
The provided comparison demonstrates PLA prints using identical settings:
* **Left Print:** No active cooling fan
* **Right Print:** 100% fan speed post-first layer
**Key Factors**
* **Material Behavior:** PLA's rapid solidification benefits from forced cooling
* **Layer Adhesion:** Controlled cooling prevents warping during crystallization
* **Quality Assurance:** Consistent fan activation maintains dimensional accuracy
**Implementation Guidelines**
* **First Layer Protocol:** Disable cooling during initial layer deposition
* **Fan Ramp-Up:** Gradually increase fan speed during second layer initialization
* **Hardware Verification:** Confirm fan functionality before extended prints
Active cooling fans, while potentially detrimental to layer adhesion with certain materials, remain essential for PLA printing. Absence of active cooling during PLA deposition consistently results in surface imperfections and top-layer curling.
**Material-Specific Guidelines**
* **PLA Requirements:** Mandatory active cooling for optimal surface finish
* **General Protocol:** Consult manufacturer specifications for filament-specific cooling needs
**Environmental Factors**
* **Temperature Sensitivity:** Excessive ambient heat exacerbates curling, particularly in enclosed chambers
* **PLA Chamber Use:** Avoid enclosed environments due to PLA's low glass transition temperature (\~60°C)
* **General Enclosure Rules:** Open chamber configurations recommended for materials without warping tendencies
**Implementation Strategies**
* **Ventilation Requirements:** Maintain open-air environments for PLA printing
* **Enclosure Management:** Remove lids/open doors during PLA deposition
* **Thermal Monitoring:** Verify chamber temperatures remain below material-specific thresholds
**Technical Rationale**
* **Crystallization Control:** Forced cooling accelerates PLA solidification
* **Warping Prevention:** Ambient temperature regulation maintains dimensional stability
* **Material Compatibility:** High-temperature materials (e.g., ABS) typically require enclosed chambers, unlike PLA
### **Not enough time for layers to cool**
If you are printing a small section on your print in which each layer prints on top\
of each other in quick succession, then the previous layer may not have been given enough time to cool. This is why the “Minimum Layer Time” setting exists in Cura under the “Cooling” section.
**Layer Time Management**\
A 3-5 second minimum layer time proves effective for most materials. When enabled, the printer pauses if layers complete faster than the set duration (e.g., 3 seconds), preventing premature deposition on uncooled layers. Combining this with Cura’s “Lift Head” feature enhances cooling by physically separating the nozzle from the print during pauses.
**Layer Height Considerations**
* **Low Layer Risks:** Thinner layers (e.g., 0.1mm) exhibit reduced rigidity compared to thicker ones (e.g., 0.3mm), increasing curling susceptibility
* **Solutions:** Increase layer height or print speed to improve structural stability
**Temperature Control**
* **Extrusion Guidelines:** Operate within manufacturer-specified temperature ranges
* **Small Nozzle Protocol:** Reduce temperatures to the lower end of recommended ranges when using sub-0.4mm nozzles with thin layers
**Support Structure Optimization**
* **Material-Specific Angles:**
* **PLA:** Supports recommended at ≥55° overhangs
* **ABS/ASA:** Supports required at ≥45° due to cooling restrictions
* **Rationale:** Restricted fan use on warping-prone materials necessitates conservative support thresholds
**Material Handling**
* **Moisture Mitigation:** Curling persisting after other adjustments indicates potential filament hydration
* **Drying Protocol:** Dehydrate spools using filament dryers or controlled heating environments
**Implementation Matrix**
| Issue | Solution | Technical Rationale |
| ------------------ | ---------------------------------- | -------------------------------- |
| Fast layers | Enable 3-5s layer time + Lift Head | Prevents heat accumulation |
| Thin layers | Increase height/speed | Enhances layer rigidity |
| High temps | Lower nozzle temperature | Reduces material plasticity |
| Unsupported angles | Adjust support thresholds | Compensates for limited cooling |
| Moisture | Dry filament | Eliminates steam-induced warping |
## **Summary of ways to reduce curling of layers and angles on 3D prints**
* Make sure your active cooling fan is on if your material calls for it. 100% fan\
speed is recommended after the first layer when printing in PLA.
* Make sure the ambient air is not approaching the glass transition temperature\
of the material you are printing. PLA should not be printed in a fully enclosed machine.
* Have your minimum layer time set to at least 3 seconds in Cura so that each\
layer has enough time to cool.
* Low layer heights have less rigidity, meaning increasing your layer height or\
your print speed will help.
* Reduce your printing temperature, especially if printing at low layer heights on\
small nozzle diameters.
* Turn on support structures and reduce the angle for when they are required,\
particularly with materials that cannot use an active cooling fan.
* Remove moisture in your material if you tried all of the above methods.
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