3D Printing Layer Separation and Splitting: Causes and Tips to Avoid them
3D prints cracking. Image Credits: geeetech.com
In 3D printing, Layer separation is a problem that causes vertical layers to split apart. This is the number one cause of print failures in FDM/FFF printing. Adhesion between layers creates a bond between them. Overhangs and bridges are prime locations for layer separation because there is no support below them. They have to rely entirely on adhesion with the layers above and beside them.
On the other hand, Layer Splitting occurs when individual layers separate from each other horizontally or along the length of an object, causing horizontal cracks. Often these splits occur after the object cools down. This means you can't see them during production, indicating most people think it's only layer separation that affects prints.
3D Printing Laser Separation and Splitting
There are a few reasons why splitting might occur. One is that the plastic cools too quickly on the print, so after a layer is completed, it doesn't have enough time to bond with the layer below it.
Sometimes 3D printers have trouble getting hot enough for some materials, resulting in splitting or cracking of layers. This can be avoided by taking slower prints at a lower temperature. Another reason could be a filament problem. Either poor material quality from an unreliable supplier or poorly-set extrusion parameters in your machine's firmware/software results in visibly thinner lines of plastic being laid down compared to other layers nearby.
What causes Layer Separation and Splitting?
This usually occurs when 3D printing overhangs or thin structures, where the printed layers are not fully bonded. Lack of support (in FDM/FFF printing) or infill (in SLS printing), weak structures in areas with unsupported geometry, and general printer settings need to be reviewed when you see splitting occurring in your prints.
If this occurs in an area around the outside edge of a model, these are likely caused by poor outer perimeter settings. Layer adhesion is crucial for successful border extrusions because there is nothing below supporting them - they have to rely entirely on being attached to the previous layer. If it's happening just inside that border, then another cause could be that your interior fill angle is set too steep, so the nozzle isn't laying down plastic across the whole circumference of your object.
Tips to avoid Layer separation and Splitting in 3D printing
There are a myriad of different prints, prints with different speeds, different materials, different nozzles or temperatures. This means there are many possible solutions to this problem. In this guide, we discuss 12 tips that will help you avoid layer separation and splitting.
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Slowing down the print speed
3D printing in progress. Image source: Pixabay
Printing at lower speeds can significantly reduce splitting, especially if that occurs due to the rapid cooling of the material. However, it might not be practical for all types of prints as it's often necessary to use higher speeds for larger objects or parts with complex geometries because it reduces the amount of time needed to print larger items. You may want to experiment with different speeds on smaller items before deciding on a final setting for full-sized parts.
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Increasing Printing Temperature
Increasing temperature can lead to better adhesion between layers, but keep in mind that it can also increase the likelihood of warping. If you are getting layer splitting, try running the printer hotter than usual until you stop seeing this problem. If your printer has a heated bed, set it to 70 degrees or more to avoid warping. You should also use materials designed to prevent printing at higher temperatures (i.e., ABS instead of PLA).
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Reduce layer height
Layer height is directly related to how much plastic is extruded per line and how much time it takes for each layer to cool before another layer is placed on top of it; this makes thin layers especially susceptible to breakage when cooling down after printing due to rapid solidification. For example, if you reduce from a layer height of 0.3mm to 0.1mm, the actual volume of plastic being printed will decrease by approximately half (since it is spread over twice as many layers), but the time each individual line of plastic takes to cool after printing will also be reduced by almost four times (because there are many more layers with which the heat can transfer away).
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Printing Inside Out
Some printers allow you to print with soluble support structures to increase strength and stability for overhangs or fine parts, but these soluble materials must be removed post-printing, generally with hot water or other chemicals. If sufficient care is taken during this process, they're not left in any way harmful to the final printed object.
FDM printers that allow printing on the inside of models (using soluble support materials) during construction can avoid some degree of splitting and layer separation because there is no unsupported overhang. However, the time taken to print this way means that it's probably not practical for larger prints; besides, this method also increases the chance of warping even more than regular printing.
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Use a Faster Cooling Fan
Printing with a faster cooling fan will reduce layer separation. A fast-moving airflow onto freshly deposited plastic quickly cools down each new layer, so adhesion between layers is better. If you have an air-cooled printer without a specifically designated "cooling fan," try using one from your hot-end instead.
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Adjust Retraction Distances and Speeds
If you have a dual-extruder 3D printer, check the settings for the second extruder because it could be pulling away too much plastic from the first nozzle. To fix this problem, reduce print speed on the second extruder and increase speed on the primary nozzle to match up more closely. You can also try increasing retraction distance or disabling retraction completely for this second extruder if it is only slightly misaligned with the first one.
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Increase the Weight of Bed/objects being Printed
If an object is not sticking well to a heated build plate, printing with increased weight on top of the object should help avoid layer splitting because there will be a higher force pressing the object in question into the bed.
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Reduce Movement Speed on the X/Y axis
Reducing your print speeds when traveling across an unsupported span will also help avoid layer separation by allowing enough time for each individual layer to cool down before being put under stress from another layer being placed on top of it. However, too low a print speed will result in a longer print time and possibly lower quality output due to extra finishing work afterward. You can use this setting during large prints or only when printing overhanging regions with insufficient support from previous layers.
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Use a Different Filament Color
Changing filaments is a subjective solution that may not always be practical depending on what type of printer you have and the material you are trying to print with. However, some users have reported good results by changing the filament during a print in the middle of an unsupported region. The previously extruded plastic supports the new filament to be printed at reduced speed and/or thickness and avoids layer separation.
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Reduce Infill Density
The actual volume of material used in a print is generally significant when avoiding splitting and layer separation. If there is too little or too much, it will either not contain or stress separate layers enough, respectively. This is caused when the z-axis code instructs each extruder to deposit more than one "pass" along their designated paths, which can throw off the timing necessary for proper adhesion between layers leading to deformities.
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Use Support Material
Adding extra support material can help avoid layer separation and splitting by itself because at least one other object gives the overhanging layers something else to bond with instead of only depositing lines directly on top of previous ones. However, if you vary where you allow it to be placed in your model (see next section), you can strategically place it where overhangs are more likely to exhibit deformation or deformity due to layer separation. There are also supports designed explicitly for bridging, which provides an extra bridge of material underneath unsupported spans that acts as another anchor to help hold them in place.
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Change Where you use Support Material
Using the same idea as the previous tip, selectively placing your support material will give you more control over where deformation is likely to occur. If your model is particularly tall or wide, consider using supports with a shorter distance between each layer (called "distributed support" because it's less concentrated) to reduce the amount of force taken on by individual layers. If needed, you can surround thin components with long-distance supports (called "compacted support") that will distribute most of its force into those specific regions instead. For example, this method could be helpful with large flat surfaces by using compacted supports to distribute force more evenly along the surface rather than concentrating it all in one spot.
Final Thoughts
While the settings we've mentioned in this guide can effectively reduce layer separation and splitting issues, that is not to say that using them will guarantee your 3D prints become flawless overnight. Many factors contribute to how each filament comes out of your printer, so take some time to examine if you can find any patterns about how certain properties seem more likely than others where layer separation occurs. This article doesn't intend on offering a "one-size-fits-all" solution but simply suggestions on what may help you get started down the right path of isolating the problem areas in your models.
Author Bio:
Samuel Matthews is a 33 years old designer from Manchester. He has also worked as a journalist writing his own detective story. Mathews likes meeting different people and learning new things. He also helps with online assignments and reviews several essay writing services during his free time. He believes that NinjaEssays service is good for this. Mathew’s hobbies are traveling, sports and drumming.
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