Glossary · Filament

TPU

A soft, rubbery printing material. It is used, for example, to print phone cases, seals or non-slip feet.

Explained in more detail

Thermoplastic polyurethane. The hardness is given in Shore A, 95A is common, and softer grades (85A to 90A) are more difficult. Print temperature 210 to 230 °C, bed 40 to 60 °C, low volumetric flow rates. A direct drive extruder with a short, guided filament path is almost essential. Hygroscopic and prone to stringing, so keep retraction low. Very abrasion-resistant and impact-resistant.

Where does the term come from?

TPU stands for thermoplastic polyurethane. Thermoplastic means that the plastic becomes soft and mouldable when heated (Greek thermos = warm). Polyurethanes were developed in 1937 by Otto Bayer.

In practice

For getting started, choose 95A; 85A and softer need a very good extruder.
Print slowly, often 20 to 40 mm/s; too high a speed is the most common cause of failure.
Dry at 50 to 55 °C for 6 to 8 hours before printing.
You control softness through the infill: a part with 10% infill yields much more than one with 50%.
Feed TPU directly from the spool to the printer rather than through a multi-colour system, unless the manufacturer explicitly approves it.

Not to be confused

TPE is the umbrella term for thermoplastic elastomers, and TPU is one type of them. Filaments sold as TPE can print differently; Shore hardness and the manufacturer's specification are what count.

Frequently asked questions

Can TPU be printed with a Bowden printer?

Hard TPU at 95A often still works, soft hardly at all. The filament buckles in the long tube instead of sliding forwards.

Why does TPU tangle in the extruder?

Usually the print is too fast, the material too soft or the path to the nozzle too long. Print slower, use direct drive or choose a harder TPU.

Printers that can process TPU

According to manufacturer specifications, from the 56 printers in the wiki: