You’ve set up your printer, had many successful prints but for some reason the top layer of your prints aren’t looking their best. This is an issue many 3D printer users have dealt with. It can be devastating to have a print go perfect, until the very end where you experience pillowing, which results in a rough surface at the top of your prints.
To help users out I’ve put together an easy ‘how-to guide’ on fixing top layer issues (pillowing) with a few easy methods for you to try out now.
What is Pillowing Exactly?
Pillowing is simply a phenomenon that occurs which leaves the top layers of your prints rough, unclosed, uneven and bumpy. Just an all-round pain to experience, especially after a long print. Unfortunately, there isn’t a type of filament or printer which is completely immune to pillowing, but some are less likely to be affected than others.
The effects of pillowing is very similar to warping but it occurs at the end of a print rather than at the start. It produces a pillow-shaped pattern at the top, hence the well-fitting name. It usually effects prints that have a large, flat top surface.
The top of a print will have a type of rough and bumpy pattern that represents the infill directly below the top layers.
Why Does Pillowing Happen in the First Place?
There are two main reasons for this happening:
- Insufficient cooling – causing the filament to warp away from the infill up towards the nozzle then it cools there and causes this effect. This is because the material gets tight and sticks over the infill but warps over the voids below. Your layer cooling fans might also play a part where they aren’t strong enough to get the material to the correct temperature to avoid this. If you are printing too fast your materials may not have enough time to cool properly and produces the same results.
- Not enough supporting material – at the top of a print to complete the print and close it. On top of this, if you don’t have enough solid top layers to your prints, pillowing can occur easier.
Simply put, this issue of pillowing mainly appears because of incorrect print settings and improper cooling. If you want a quick solution to improve your print quality, get yourself the widely-popular Noctua NF-A4 fan.
Prints that are set up with small layer heights are affected more so because materials warp easier when there is less support underneath each layer.
Another thing to know here is that 1.75mm filaments (printer standard) are more likely to be affected than the 2.85mm filament counterparts.
Softer filaments such as TPU, and higher temperature filaments such as ABS and polycarbonate do have more pillowing issues than harder filaments, but these are problems which can be solved with a few different methods.
Easy Ways to Solve Pillowing Issues
1. Increase Top Layer Thickness
Even though pillowing is a result of imperfect cooling, the issue comes about from the addition of a thin top surface.
Top layers of a print is what influences the pillowing effect. The more top layers that you have, the more chances for your printer to cover over the gaps.
There is an easy fix for this problem.
The first thing you should try to prevent pillowing/rough top layers is adding more top layers to your prints. This is done quite easily from your slicer settings by increasing the ‘top thickness’.
Each extra layer that you have on your print, it means that there are more opportunities for the layer to melt away the possible pillowing effect that you may have encountered underneath.
I’d recommend having a top layer thickness which is six to eight times the layer height, which should be more than enough to alleviate any pillowing issues that you have been experiencing.
So if you are printing an object using a 0.1mm layer height, you would want a top/bottom thickness of 0.6-0.8mm so that the top surface of your print can close and prevent the sagging/pillowing effect.
Keep in mind though, if you have really thin layers, your print is more susceptible to warping and curling because the layers become more fragile. In this case, you’ll need more layers at the top to close the print properly.
Some people say to keep your top layer height total to roughly 1mm, so:
- Layer height of 0.1mm – print 9 top layers
- Layer height of 0.2mm – print 4 top layers
- Layer height of 0.3mm – print 3 top layers
This isn’t required but if you want to be on the safe side, it’s a good rule of thumb to go by.
2. Increase Infill Density Percentage
Increasing your infill density percentage does a similar thing with increasing the number of top layers.
This method helps by giving the top layers more surface area to be supported by, making it fuller and smoother rather than rough and low-quality.
Pillowing happens because of the gaps between the infill, for example, if something was printed at a 100% infill density, there would be no chance of pillowing because there aren’t any gaps in the middle of the print. So reducing these gaps by increasing the infill below the top layer it reduces the chance of it happening.
When you are printing at lower infill levels such as 0%, 5%, 10% you are more likely to notice pillowing effects. It really does depend on the design of your print, if you have a delicate product and need a lower infill, you want to compensate by using a stronger material.
Some printers are more prone to pillowing than others but as time goes on, printers are developing at a high rate in terms of quality.
Some prints will print just fine at 5% infill, other may struggle.
Comparing the two methods above, the top layer method does usually use more filament, but depending on what functionality you have with your part it could be a better idea to use the infill method.
Some 3D printer users have reported having a minimum infill percentage of 12% should hold up and reduce pillowing.
The video below shows just how easy these two methods are.
3. Decrease Printer Speed
Another method you can use is to lower the print speed for your top solid layers. What this does is give your top layers more time to cool off before they start peeling away. When your layers have more time to cool off it gives the material time to harden, giving it more support and strength.
It doesn’t necessarily reduce your layer adhesion, but it does prevent your prints warping away which forms the pillow on top.
This may take a bit of trial and error but once you get the right settings down, you’ll be printing objects successfully.
When it comes to print quality, most of the time you have to balance overall printing times with lower or higher quality. It’s a necessary trade-off but it does show its benefits when your prints are finished.
There are methods out there where you can decrease print times and keep that high quality you desire, which leads us into the next method.
4. Improve Your Cooling Fans
One method requires the modification of your printer and is using a cooling fan.
Some printers already come with a layer cooling fan, but they may not work efficiently enough to correct the pillowing issues you are having. Many times, a 3D printer is equipped with cheaper parts to keep costs down.
One thing you can do if you already have a cooling fan is to print a more efficient layer cooling duct, where the airflow is direct all the way around the nozzle or directed specifically at the part, rather than at the heater block.
If this doesn’t work or you don’t have one, getting a new layer cooling fan is the best idea.
There are many premium parts that you can make use of that get the job done much more efficiently than the standard part.
When it comes to cooling fans, the Noctua NF-A4 is one of the best out there. The advantages for this high-rated premium fan is it’s superior quiet cooling performance and great efficiency. It’s a cooling fan that has saved 3D printer users countless hours on failed prints.With this fan, your cooling issues should be eliminated.
It’s aerodynamic design offers superb running smoothness and amazing long-term durability.
Turning your fan on is the first obvious step, which can sometimes be done in some slicer programs. If you can’t set your fan in your slicer, it is possible to manually edit the G-code using the M106 command. You shouldn’t have to do this in most cases, but it isn’t too difficult to do with a guide.
Something as simple as a desk fan could help if you aren’t comfortable installing a cooling fan onto your 3D printer. However, cooling fans may just blow the cool air towards specific parts of your prints and not all over, which is where you might see pillowing.
Keep in mind, depending on what fan you have you might not want to run it at maximum speed. Some materials are more sensitive to warping and pillowing so when you have the fan’s air pressure blowing at a print, it increases the chances of warping. There is such thing as rapid cooling, and it can have a negative effect on the quality of your prints.
With materials such as Nylon, ABS and HIPS you ideally want a low fan speed.
If the plastic doesn’t cool enough, it causes the material to either hang down or curl up in the areas where the infill lines are. It creates an uneven surface which is a problem for the next layer that goes on top of it. That’s when you get your rough, bumpy top surface.
5. Lower Your Printing Temperature
In some cases, lowering your printing temperature could help due to the nature of the issue. This can cause more issues than it solves though, so it isn’t a solution to jump straight into. It could make your prints start under extruding.
I’d definitely try the previous methods before pulling this one out the bag. Materials usually have a temperature range to print at the best quality, so once you’ve found a perfect temperature for your setup, you don’t usually want to be changing it around.
Depending on what material you are using to print, some have cooling issues such as the high temperature filaments out there. You can avoid having to play with temperature settings to prevent pillowing if you implement the other methods with more intensity.
This method works the best with the high temperature materials because they take a longer time to cool down and get to a firmer state. Big changes in the temperature of these materials as they are extruded onto the build surface make them more likely to warp.
When you lower the temperature of the nozzle’s hot end for the top layers, you effectively prevent pillowing as you are combating the issue directly. Having your cooling fan running at a high power to assist the cooling is recommended with these materials. You want to aim to cool down the extruded filament as quick as you can so it can set into it’s intended place properly and doesn’t sag into the spaces between the infill.