What does TPU 95A mean?

The number is its Shore A hardness: the higher, the stiffer. A 95A is one of the hardest flexibles and therefore one of the easiest to print; Prusa explains that the softer the filament, the harder it is to print.

Can you print TPU with the AMS?

On Bambu Lab printers, the machine itself warns that its TPU 95A HF isn't compatible with the AMS: a system that pushes filament through long tubes can't reliably push something that soft. You print it from the external spool.

How fast should you print TPU?

Slowly. Prusa gives 20 mm/s as a typical speed and 30-40 mm/s as the maximum; Polymaker lists 20-40 mm/s for its TPU95. Going faster raises the risk of clogs or of the filament tangling in the gears.

Why does TPU stick so hard to the bed?

Because it bonds very well to smooth PEI, so much that it can damage it when you remove the part. Prusa recommends glue stick as a separator on smooth or satin sheets; textured sheets don't need it.

Materials

How to print TPU (flexible filament) without clogs

TPU is the filament for anything that has to bend without breaking: cases, gaskets, wheels, bumpers, straps. It's also the one that jams most often for first-timers, because it behaves the opposite way to PLA: you need to go slowly, with little pressure on the extruder and hardly any retraction. Here's what it is, whether your printer can handle it and the settings manufacturers recommend.

What TPU is and what "95A" means

TPU is a type of TPE (thermoplastic elastomer): a plastic that behaves like rubber. What sets one flexible apart from another is its Shore A hardness, the number next to its name. According to Prusa, TPU usually sits between 60A and 90A, and there are harder versions, like the very popular 95A ones (for example, Polymaker's PolyFlex TPU95, which according to its datasheet stretches to more than three times its length).

The practical rule, also from Prusa: the softer the filament, the harder it is to print. If it's your first flexible, start with a 95A.

Shore A hardness of flexibles: TPU usually runs 60A-90A according to Prusa, and the "95A" ones sit at the hard end.

Can your printer handle TPU?

What matters most is where the extruder sits. A flexible filament pushed through a long tube behaves like a rope: it bends, presses against the tube walls and jams. That's why TPU works far better with a direct-drive extruder (mounted right above the hotend, with a very short path) than with a Bowden one (on the frame, pushing through a tube).

Why direct drive helps so much with TPU: the soft filament has no long tube to buckle in.

The good news is that direct drive is now the norm: of the 71 FDM printers in our catalogue that publish this, 68 have it. You can check yours in the material checker, which takes the extruder type into account for its TPU verdict.

Multicolour systems are a special case: on Bambu Lab printers, the machine itself warns that its TPU 95A HF isn't compatible with the AMS, because a system pushing filament through long tubes has the same problem as a Bowden. TPU is printed from the external spool.

The settings manufacturers recommend

Nozzle temperature: Prusa recommends 230-245 °C, depending on hardness and brand. Use your filament's datasheet as the starting point.
Bed: 60-75 °C according to Prusa (higher for bigger parts).
Speed: slow. Prusa gives 20 mm/s as typical and 30-40 mm/s as the maximum; Polymaker, 20-40 mm/s. In its Flexfill profile Prusa also caps flow at 1.5 mm³/s (about 17 mm/s with 0.2 mm layers): the most reliable way to stop the slicer running too fast. If the idea sounds familiar, it's the hotend's volumetric flow.
Retraction: low or none. Prusa recommends lowering it as far as possible and, if you can't find the value, turning it off and raising it bit by bit; Polymaker's datasheet uses 1 mm.
Extruder: loosen the idler so the gears push gently; if they press too hard, the filament tangles in them (Prusa).
Part cooling fan: here the sources disagree. Prusa advises turning it off in its flexibles guide, while Polymaker's datasheet has it on for its TPU95. Start with what your filament's maker says.

The bed: sticky, but not too sticky

TPU bonds very well to PEI, so much that removing the part can tear off some of the surface. Prusa recommends a layer of glue stick as a separator on smooth or satin sheets; textured sheets don't need it.

Moisture: the silent enemy

Flexibles absorb moisture from the air and print much worse when wet (Prusa): more strings, bubbles and a rough surface. Keep it in a bag with desiccant and, if it's been open a while, dry it before printing. If what you're seeing is strings, how to fix stringing covers the other causes.

Designing for TPU

You decide the flexibility: fewer perimeters and fewer top and bottom layers give a softer part; more infill and perimeters, a tougher one (Prusa).
Avoid bridges and overhangs: TPU handles them poorly, and supports are hard to remove.
Good uses: shock-absorbing washers and spacers, phone or camera cases, wheels and bumpers.

Frequently asked questions

What does TPU 95A mean?: The number is its Shore A hardness: the higher, the stiffer. A 95A is one of the hardest flexibles and therefore one of the easiest to print; Prusa explains that the softer the filament, the harder it is to print.
Can you print TPU with the AMS?: On Bambu Lab printers, the machine itself warns that its TPU 95A HF isn't compatible with the AMS: a system that pushes filament through long tubes can't reliably push something that soft. You print it from the external spool.
How fast should you print TPU?: Slowly. Prusa gives 20 mm/s as a typical speed and 30-40 mm/s as the maximum; Polymaker lists 20-40 mm/s for its TPU95. Going faster raises the risk of clogs or of the filament tangling in the gears.
Why does TPU stick so hard to the bed?: Because it bonds very well to smooth PEI, so much that it can damage it when you remove the part. Prusa recommends glue stick as a separator on smooth or satin sheets; textured sheets don't need it.

Sources

Prusa Knowledge Base — Flexible materials
Prusa Blog — How to print with flexible filament
Polymaker — PolyFlex TPU95 technical datasheet (PDF)
Official Bambu Lab forum — "Bambu Lab TPU 95A HF" is not supported by AMS (printer warning and user reports)
hotend catalogue data: extruder type as declared by each manufacturer.