TPU Filaments
Thermoplastic Polyurethane
TPU (Thermoplastic Polyurethane) is the most common flexible filament in FDM printing. It combines rubber-like elasticity with decent abrasion and chemical resistance, making it useful for functional parts that need to flex, compress, or grip. Hardness varies by grade — Shore 95A is relatively stiff and close to a hard rubber, while Shore 83A is very soft and can be hard to feed reliably through standard extruders. The main printing challenge is the material's flexibility itself: floppy filament buckles easily in Bowden tubes and jams if the feed path is not tight. Direct-drive extruders handle TPU far more reliably than Bowden setups.
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What is TPU used for?
- Phone cases, protective covers and bumpers
- Gaskets, seals and flexible joints
- Shoe insoles and wearable accessories
- Anti-vibration mounts and dampeners
- Cable management, strain reliefs and grommets
How to print TPU
Print TPU at 220–240 °C with a bed between 30 and 60 °C (a warm bed at 40–50 °C improves first-layer adhesion). Reduce print speed significantly compared to rigid filaments — 20–30 mm/s is typical for reliable results with softer grades; stiffer 95A grades tolerate 40–60 mm/s. Disable or minimise retraction: long retraction distances cause the filament to buckle in the feed path and jam. A direct-drive extruder is strongly recommended; Bowden setups can work with very stiff (95A) TPU but are unreliable with softer grades. No enclosure is needed. TPU is hygroscopic — dry your spool at 70 °C for several hours if it has been stored unsealed.
Advantages
- Flexible and elastic — bounces back after deformation
- Good abrasion and chemical resistance
- No enclosure needed
- Prints without warping on most surfaces
- Wide range of hardness grades (80A–98A)
Limitations
- Requires slow print speeds — increases print times significantly
- Bowden extruders struggle with soft grades
- Stringing can be difficult to control
- Highly hygroscopic — must be stored dry
- Not suitable for rigid structural parts
Common variants
TPU is primarily categorised by Shore hardness; specialty fills also exist:
- Shore 95A (stiff TPU)
- The most printable grade — close to a hard rubber. Compatible with Bowden extruders. Good for cases, hinges and snap-fits.
- Shore 83–87A (soft TPU)
- Very flexible and stretchy. Requires a direct-drive extruder. Ideal for insoles, grips and highly conformable parts.
- TPU-CF
- Carbon-fibre-filled for higher stiffness and dimensional accuracy while retaining some flexibility. Abrasive — hardened nozzle needed.