TPU is rubber-like: flexible, grippy, and durable under repeated compression and abrasion. It’s harder to print than PLA but not by a lot on a direct drive printer. The main challenges are that it doesn’t like fast retraction, doesn’t like fast print speed, and absorbs moisture enough to cause problems in humid climates.
Where TPU Makes Sense
Phone cases, wearables, gaskets, seals, wheel tires for RC cars and robots, protective bumpers, cable strain reliefs, and any functional part that needs to compress or flex rather than resist rigidly. Shore 95A (firm flexible) handles structural loads that 85A can’t. Shore 85A is more rubber-like and better for grip surfaces.
Where TPU Underperforms
High-heat applications above 60°C — TPU softens and deforms under sustained heat. Dimensionally precise parts — TPU’s flexibility makes measuring and fitting difficult. Anything requiring Bowden extrusion — the flexibility of TPU causes it to buckle in a Bowden tube at normal print speeds, and the workarounds are more trouble than a direct drive extruder.
Direct Drive vs. Bowden
On a direct drive extruder, TPU prints reliably at 20–30mm/s. The short filament path prevents buckling. On a Bowden setup, the long tube between the extruder and hotend allows the soft filament to compress and buckle instead of advancing — you get under-extrusion, clicking, and jams. If you have a Bowden printer and need to print TPU, reduce speed to 10–15mm/s and disable retraction entirely. Results will be marginal.
Temperature
Nozzle: 225°C is a good starting point for most 95A TPU. Softer grades (85A) print better at 220°C. Harder Shore variants (98A, 99A) may need 235°C. If you see under-extrusion at 225°C, raise temperature before slowing speed.
Bed: 45–50°C on PEI. TPU adheres very well to PEI — often too well. Parts can be difficult to remove if the bed is too hot or the Z-offset is too low. If the part sticks permanently, wait until the bed cools to below 30°C before flexing the part off. Avoid scratching PEI with tools.
Retraction
Use 0–1mm retraction on direct drive. TPU’s elasticity stores retraction distance as spring compression in the extruder path — too much retraction doesn’t actually pull the nozzle dry, it just bounces back and over-extrudes on the restart. If you’re getting stringing on TPU, lower retraction is usually better than more. Dropping from 1mm to 0.3mm often reduces stringing more than increasing retraction.
Speed
20–30mm/s total. Infill and perimeters at the same speed — don’t set infill faster than perimeters on TPU. Faster speeds cause buckling in the extruder path even on direct drive setups. Accept that TPU prints slowly.
Fan Speed
30–50% fan. Some cooling helps bridge quality and dimensional accuracy without hurting layer adhesion significantly. Full fan (100%) on TPU reduces inter-layer bonding and makes the print more brittle along layer lines — flexible prints that snap along layer lines have usually been over-cooled.
Moisture
TPU absorbs moisture within 4–8 hours of open air exposure in humid climates. Signs: increased stringing, audible popping during printing, rough texture. Dry at 55°C for 4–6 hours. TPU’s moisture sensitivity is moderate — worse than ABS, better than Nylon. Store in a sealed bag with desiccant.