TPU: when you need a part that bends instead of breaking
What TPU is, what it is genuinely for, how it differs from a rigid plastic, and what to expect from a printed flexible part.
Every other material we print is rigid: it flexes a little and then snaps. TPU does not. It is an elastomer — plastic that behaves like rubber — and it stretches, squashes and returns. It is the material for parts where stiffness is the problem rather than the solution.
What it is genuinely for
- Seals, bump stops and washers: replacing the rubber that got lost or went hard.
- Non-slip feet and pads for furniture, equipment and cases.
- Sleeves and protectors: for a controller, a sensor, an instrument that gets dropped.
- Parts that damp vibration, especially anything bolted to a motor.
- Living hinges and clips that must open and close many times without fatiguing.
- Soft jaws to hold a delicate part without marking it.
Hardness is not one thing
TPU is measured on the Shore A scale. A 95A TPU — the usual one in printing — is like a skate wheel or a firm shoe sole: flexible, but with body. It is not silicone, and it is not soft bung rubber. If you expect something that squashes between your fingers like a stress ball, printed TPU will feel hard to you.
What to know before ordering it
| Aspect | What to expect |
|---|---|
| Speed | Prints considerably slower than PLA. The same part costs more in machine time. |
| Fine detail | Worse than rigid. The material is elastic and edges come out slightly rounded. |
| Tolerances | Looser. A flexible part deforms as you measure it, so it is not a material for precision fits. |
| Temperature | Holds more than PLA, around 80 °C, and does not go brittle in the cold. |
| Sealing | A printed seal closes far better than a rigid one, but it still has layers. It is not an O-ring. |
When it is not the answer
If the part has to carry a load without deforming, TPU is precisely the opposite of what you need: it gives. And if you want a rigid part to survive being dropped, the answer is often not TPU but PETG, which bends a long way before breaking and holds its shape. TPU is for when deforming is the job.