TPU

TPU (thermoplastic polyurethane) is a flexible, rubber-like material. The finished part stretches, bends and springs back without breaking. Stiffness is set by Shore hardness: 85A is soft like an eraser, 95A is springy and closer to hard rubber. TPU is harder to print than rigid plastics because of its soft strand.

What it is good for

• Phone cases, protective bumpers
• Gaskets, seals, dampers
• Straps, hinges, flexible joints
• Wheels, treads, anti-vibration feet

Where NOT to use it

• Rigid loaded parts — TPU is too soft
• High speed on a Bowden extruder — the strand buckles and skips
• Tight-tolerance dimensional parts — flexibility hurts accuracy
• Small parts with sharp geometry — TPU rounds them off

How to print

• Nozzle temperature: 210–240 °C
• Bed temperature: 30–60 °C
• Cooling: 30–100% depending on hardness
• Speed: 15–40 mm/s — slow! TPU hates rushing
• Extruder: direct drive preferred; on Bowden, only rigid 95A and very slow
• Retraction: minimal (0.5–2 mm) — or the strand jams in the extruder

Drying and storage

TPU is very hygroscopic — it absorbs moisture fast. Wet TPU bubbles, hisses, and loses elasticity.

• Drying: 50–60 °C for 6–8 hours (before every print if the spool sat open)
• Storage: airtight box with silica gel — strictly
• Signs of moisture: bubbling, hissing, heavy stringing, brittle part

Pros and cons

• Flexible and elastic, springs back well
• Wear-resistant, resists oils and abrasion
• Absorbs vibration and impact
• Available in different hardnesses

• Hard to print — needs low speed
• Works best on direct drive
• Very hygroscopic
• Prone to stringing