TPU — From Flexible Phone Cases to Shock-Absorbing Parts, a Versatile Material
Thermoplastic Polyurethane
What Is TPU?
TPU (Thermoplastic Polyurethane) is a thermoplastic elastomer that combines the processability of plastic with the elasticity of rubber. In 3D printing, it is synonymous with flexible materials — the objects you print can bend, stretch, compress, and spring back.
Key Properties
- Print difficulty: Hard. TPU is flexible, making it prone to buckling and clogging during extrusion and feeding. A direct-drive extruder and slow print speeds are essential for good results.
- Shore hardness: Common TPU grades range from 85A to 95A. 85A is softer (like a rubber band), 95A is firmer (like a car tire). Beginners are advised to start with 95A.
- Strong layer adhesion: TPU layers fuse together tightly, almost never delaminating — a major advantage of flexible materials.
- Wear, oil, and chemical resistant: TPU’s physical durability far exceeds that of PLA and PETG, making it ideal for functional applications.
- Downside: retraction is difficult. The flexible filament deforms easily in the extruder gears, and improper retraction settings can make things worse. Many experienced printers simply disable retraction and rely on “wiping” moves to reduce stringing.
Recommended Print Settings
| Parameter | Recommended Range |
|---|---|
| Nozzle temperature | 220-235°C (225°C for 95A) |
| Bed temperature | 40-60°C (55°C is the sweet spot) |
| Print speed | 15-35 mm/s (slow is key; too fast causes slipping) |
| Layer height | 0.16-0.24 mm |
| Cooling fan | 0-25% (flexible materials need heat for layer bonding) |
| Retraction | Disable if possible. If needed, ≤ 1 mm distance, ≤ 20 mm/s speed |
| Extruder | Direct-drive strongly recommended (Bowden tubes struggle significantly) |
Best Uses
- Phone cases, remote control covers
- Drone blade guards, landing gear bumpers
- Shock pads, anti-slip feet
- Robot tires, crawling robot feet
- Wearables (watch bands, headphone ear cup prototypes)
- Seals and gaskets
Recommended Brands
- Bambu Lab TPU for AMS ($17-$25/kg): Optimized for AMS, hardness 95A, much smoother printing than traditional TPU.
- Polymaker PolyFlex TPU95 ($14-$22/kg): Industry benchmark flexible filament, consistent quality and batch-to-batch reliability.
- eSun eTPU-95A ($11-$17/kg): One of the best value TPU options, suitable for high-volume and batch printing.
- SainSmart TPU ($13-$18/kg): Popular brand on Amazon, well-reviewed by beginners, includes detailed parameter guides.
Beginner Tips
TPU is not a starter material. We recommend completing at least 5-10 kg of PLA printing and getting comfortable with basic parameter tuning before attempting TPU. The three keys to success are: direct-drive extruder + slow print speed + minimal retraction. If your printer uses a Bowden tube setup (like a stock Ender-3), you’ll need to convert to direct drive for reliable TPU printing.
Storage and Drying
TPU becomes extremely difficult to print once it absorbs moisture. Drying conditions: 70-80°C for 8-12 hours. Do not exceed 85°C or the TPU will melt into a sticky mass. After opening, keep it sealed in a dry box at all times.