Nowadays, 3D printers can use a wide range of filaments, from rigid to flexible, and TPU filaments are probably the most flexible filaments in the market.
Although Printing TPU can be challenging, the ability to print TPU can open lots of opportunities. With TPU, you can create specialized phone covers, flexible grippers, toys, etc.
To print TPU, you can start with a tentative setting and then change some parameters to reach your desired outcome. Note that it’s normal if the first results weren’t satisfactory. Sooner or later, you will get the gist of it.
The below table shows the setting I use for Ender 3 pro and Ployflex filament from Polymakers. The 3D printer has received some upgrades, including a direct drive system and custom filament guide. So the exact setting may not suit your printer or filament brand, but it can be a good start.
|Printing Speed||30 mm/s|
|Travel Speed||200 mm/s|
|Layer Height||0.1 mm|
|Printing Temperature||220o C|
|Build Plate Temperature||50o C|
|Retraction Speed||10 mm/s|
|Retraction Distance||1.5 mm|
Cura Settings for TPU
Flexible materials like TPU tend to jam and distort. Also, a high printing speed can cause oozing and stringing. So you need to slow down the whole process of printing.
30 mm/s is a safe speed to start with; you can always increase this speed, as long as it doesn’t affect your printing quality. But bear in mind that quality is often more important than printing time. No one wants a fast but failed product.
It’s also important to record the best setting parameters and save the profile after your successful print.
Slow Travel speed can cause more stringing by holding the nozzle in the air. However, Increasing the travel speed by too much can damage your printer in the long run. 150 to 200 mm/s is a good range, although higher values are also allowed.
Layer height is one of the most critical factors. The right height can produce even layers and improve print quality. You can set it as high as 0.3 for typical PLA prints. However, It should be much lower with more flexible filaments.
0.1mm layer height is a safe value for the beginning. Depending on the filament flexibility and manufacturer, you can increase this value up to 0.3 for less flexible filaments.
TPU filaments need better supports, and so they are more sensitive to low infill. Decrease the infill, and you will get low surface quality.
Some designs need more infill than others, but the infill percentage should be more than 30% as a general role of thumb. It’s a good idea to set the infill as high as 100% for functional parts.
The temperature has a remarkable impact on filament liquidity. Higher temperatures can improve layer adhesion but create hairy prints. High temperature can also make the filament thickness unstable as it leaves the nozzle. This phenomenon is heavily dependent on filament quality. On the other hand, low nozzle temperature will decrease layer adhesion and strings.
The optimized nozzle temperature for TPU is around 220 to 240° C. You can start with the manufacturers’ minimum recommended temperature.
Build Plate Temperature
The best amount of Build Plate Temperature depends on the printer and its bed surface. You can use more adhesives and decrease the bed temperature or increase it to get better first-layer adhesions.
However, high temperatures can cause several issues like the elephant foot problem. The best range for TPU is 40 to 60o C. Yet, you can set it as low as room temperature. This parameter usually doesn’t make problems.
Some people like to turn off retraction in Cura settings for TPU to avoid extruder jamming. However, retraction can be of great help when it comes to reducing strings and improving print quality. So retraction is preferred, especially in print designs with long travel distances. (Travel distance is the length of the path which nozzle travels without extruding filament.)
However, TPU can easily bend and distort in the extruding mechanism no matter which 3D printer you use. So if you want to use retraction, the best approach is to set it as low as possible.
A safe value for retraction speed is 10mm/s. High retraction speed can compress the filament and create buckling with sudden back pressure. So it’s not advised to set the pace higher.
The retraction distance can vary from case to case. 3D printers with Bowden tube extruders require more retraction distance than direct extruders. The Bowden tube’s length (or the distance between the drive gear and hot end) can also determine the retraction distance’s optimum value.
On average, The best retraction distance for a direct extruder is around 1.5mm. At the same time, it can be as high as 6mm for Bowden tube extruders.
Printing TPU with a Bowden tube can be tricky. There is always the possibility of your filament jamming in the tube. However, you can experiment with different settings and improve your results. Upgrading your 3D printer and adding a direct drive extruder is also another option.
In most designs, print cooling is optional. You can use it to eliminate stringing or speed up the cooling time. In intricate prints with lots of overhangs, it’s essential to cool the filaments faster. You can set the cooling fan speed to 60% for your first tries.
Build Plate Adhesion
Many filament materials need brim to avoid warping and improve bed adhesion. TPU has less tendency to warp due to its flexibility, so using this feature is not necessary. However, using a skirt can help with the first layer quality.
You should know that with slight changes, these different parameters used in Cura settings for TPU can be used in other slicers like simplify3D or Slic3r.
Recommended Cura Settings for TPU from different manufacturers
In the table below, we wrote down some of the recommended settings for different filament brands.
|Print Temperature||Bed Temperature||Print Speed|
|MatterHacker’s Pro TPU||220 – 240o C||Room Temp to 40o C||15 – 30 mm/s|
|NinjaFlex||225 – 235O C||Room Temp to 40o C||10 – 20 mm/s|
|Cheetah||230 – 240o C||Room Temp to 40o C||30 – 45 mm/s|
|Armadillo||220 – 230o C||Room Temp to 40o C||15 – 20 mm/s|
|PolyFlex||210 – 230o C||20 – 60o C||20 – 40 mm/s|
|SainSmart||195 – 230o C||40 – 60o C||15 – 30 mm/s|
These are also the best TPU filaments in the market.
Now, you should have a solid knowledge of the required settings and how to optimize them. However, you may still screw things up, but don’t worry, it’s natural. If that happened, the following text could be of help to you.
Dry the filaments
If you are doing everything right but the results are still not satisfactory, maybe it’s because your filament has absorbed moisture. The filament spools that are in humid areas can absorb water over time.
But don’t worry, they can quickly become dry again and revive; All you need to do is put them in an oven for six hours and under 130° F.
Most TPU and TPE filaments are hygroscopic to some degree and will sizzle in the hot end during print. The sizzle is caused by the absorbed water turning to steam due to the nozzle’s heat.
Voids (bubbles) in the print or the outcoming filaments in the nozzle, or excessive stringing are the apparent signs of a wet filament.
Check first layers
Great first layers are crucial for a successful print. There are a few things to consider beforehand.
- You need a good print surface. Heated glass and blue tape are proven surfaces for TPU.
- Z-offset should be in the right range. The filament has to adhere to the surface but not squish too much.
- 3D printers use different bed leveling mechanisms. So check whether the bed leveling is done well according to your experiences.