3D Printing with TPU (Thermoplastic Polyurethane) filament can be challenging, but it’s worth the effort as it offers unique properties such as elasticity, flexibility, and abrasion resistance. Here are some tips for successful 3D printing with TPU filament:
1. Slow down the print speeds: Printing with TPU requires slower printing speeds than other filaments, typically 20-30mm/s. Slower speeds allow for better extrusion control and lowers the risk of the filament slipping or clogging. Also setting the print speeds for infill, support, and walls to the same value will create more consistent forces upon the filament and less issues with extrusion flow. Doing so will take more time for printing but will result in less failed prints and wasted material.
2. Use a direct drive extruder: A direct drive extruder system, where the extruder motor is mounted directly above the hotend, is recommended for printing with TPU. It provides better filament control, improves print quality, and minimizes the risk of filament buckling or jamming.
3. Ensure proper bed adhesion: A clean and properly prepared print bed is crucial for good adhesion and preventing warping or lifting of the print. Use a textured surface like BuildTak or Kapton tape, and ensure the bed is leveled correctly.
4. Avoid overheating the filament: 3D printing with TPU can be sensitive to temperature changes, and overheating can result in stringing or blobbing. Adjust the printing temperature to the recommended range (usually between 220-240°C) and avoid prolonged exposure to high temperatures.
5. Use cooling fans carefully: Unlike most filaments, printing with TPU doesn’t benefit from cooling fans as it cools quickly and may become brittle. If you use cooling fans, make sure they are set to low speed and keep the nozzle at a safe distance from the print.
6. Experiment with retraction settings: Retraction settings can affect the quality of TPU prints. Try experimenting with the retraction distance and speed to minimize stringing and blobs. Slower and less retraction will help with grinding of filament and wrapping around drive gear(s).
7. Lower extruder tension: 3D printing with TPU and TPE benefits from a lighter grip on the filament. Ironically this is especially true for dual drive extruders. With high extruder tensions, filament wrapping or misbehaving inside of the extruder. Slower printing speeds help but will not resolve all of the issues, tension needs to be reduced. This is especially true when printing with extra soft materials like NinjaTek Chinchilla filament (75A), an extremely soft product that is useful for applications that have contact with human skin. With extra soft filaments you will find it necessary to reduce the extruder tension to point you could pull the filament out of the extruder without the tension lever release lever applied. Part of issues that occur is the TPU filament stretches from the force required to unroll from the filament spool. The stretching decreases the filament diameter momentarily in jerky motions. As filament movement and flows become unsteady the filament will buckle or squish before exiting the hotend. One temporary solution is to repeatedly hand pull filament off of the spool so it hangs loosely through out the print, this removes most of the resistance. Depending on your filament sensor type you may need to bypass it if it creates resistance on the filament. Longer term you may want to upgrade the filament reel and if appropriate the filament sensor to lower friction designs.
8. Print in a well-ventilated area: TPU can emit fumes during printing, which may irritate the eyes, nose, and throat. It’s recommended to print in a well-ventilated area or use a fume extractor.
3D Printing with TPU filament requires patience, attention to detail, and lots of experimentation. Follow these tips to achieve successful prints with TPU and enjoy its unique properties.
May the force be balanced in your 3D journey.