Filament
90A, 95A, or 95A-HF: Picking Your TPU by the Numbers
This page compares Polymaker's three PolyFlex TPU grades by Shore hardness, stretch, and print speed. It also walks through the nozzle, AMS, and extruder checks that can rule a grade out before the part's job ever matters.
The short answer
On a Bambu printer, check this first: Bambu's own guidance says to avoid printing any TPU through the AMS, at any Shore hardness, because it can get stuck in the feed tube. Feed TPU from outside the AMS instead.
Once that's settled, the choice between grades comes down to what the part has to do. Polymaker's data sheets put PolyFlex TPU90 (90A) at the highest elongation at break of the three, 592.1 ± 32.9%, and the lowest resistance to stretching, 7.1 ± 0.3 MPa at 100% strain — it moves the most for the least force, which suits a seal, a gasket, or a vibration damper. TPU95 (95A) and TPU95-HF (95A, though Polymaker states it measures closer to 98A) resist deforming more — 11.1 and 15.5 MPa at 100% strain — while still stretching 495–551% before breaking, which suits a snap-fit or a grip that has to hold its shape under load. Extruder-feed guidance follows a similar gradient, covered in full below: Polymaker recommends against Bowden for TPU90, says TPU95 also runs on a Bowden setup though faster on direct drive, and says TPU95-HF can run on an indirect (Bowden) printer too, with direct drive still recommended for its full speed range.
See Can the AMS Feed TPU, Carbon Fiber Nylon or Wood PLA? for the rest of what the AMS will and won't take, and the sections below for the nozzle, extruder, and drying checks behind these numbers.
What the Shore number means
Shore hardness is a durometer reading, not a marketing tier. A spring-loaded steel indenter presses into the material for a set time; how far it sinks in sets the number, on a 0-to-100 scale where 0 means a full 2.5mm indentation and 100 means none. Shore A and Shore D use different indenters and spring loads for different ranges: Shore A (a truncated cone, about 8.05 N of force) is built for roughly 10 to 90 on its own scale; Shore D (a sharper cone, about 44.5 N) takes over above roughly 90 Shore A. TPU95 and TPU95-HF sit at, or just past, that boundary — part of why Polymaker describes TPU95-HF as closer to 98A than a clean 95.
For a sense of scale, a comparison table on the same Wikipedia page puts automotive tire tread at about 70A and the hard wheels on roller skates or a skateboard at about 98A. All three grades on this page sit above tire tread, in hard-wheel territory. That's also part of why a 5-point jump between them reads as a bigger change than the same 5 points would be lower on the scale: Polymaker's own figures show stress at 100% strain more than doubling, from 7.1 MPa at 90A to 15.5 MPa at the HF grade, over that narrow band.
The three PolyFlex grades side by side
| Grade | Shore hardness | Density at 23°C | Stress at 100% strain | Elongation at break | Printing speed range | Drying |
|---|---|---|---|---|---|---|
| PolyFlex TPU90 | 90A | 1.12 g/cm³ | 7.1 ± 0.3 MPa | 592.1 ± 32.9% | 30–70 mm/s | 70°C for 8h |
| PolyFlex TPU95 | 95A | 1.20–1.24 g/cm³ | 11.1 ± 0.3 MPa | 551.2 ± 23.5% | 30–50 mm/s | 70°C for 8h |
| PolyFlex TPU95-HF | 95A (Polymaker: closer to 98A) | 1.16 g/cm³ | 15.5 ± 0.7 MPa | 495.8 ± 16.2% | 30–100 mm/s | 70°C for 8h |
Read it as a trade: as the Shore number goes up, elongation at break goes down and stress at 100% strain goes up. The harder grade tears sooner if you stretch it far enough, but it resists being stretched or squeezed in the first place more than the softer one does. TPU95-HF also prints across the widest speed window of the three — 30 to 100mm/s, against TPU90's 30 to 70mm/s and TPU95's 30 to 50mm/s, per Polymaker's own settings.
Whether your extruder can feed it
Polymaker publishes different guidance per grade, not one rule for 'TPU.' TPU90: use a direct extruder, not Bowden — the bigger the gap to the hotend, the harder the material is to push. TPU95: runs on most printers, but prints faster on direct drive than Bowden; Polymaker's FAQ still recommends direct drive. TPU95-HF: Polymaker's FAQ calls it 'designed to print fast on direct, geared extruders and can print even with a Bowden setup,' and says directly that it 'can be printed on an indirect drive printer' — Polymaker still recommends direct drive to reach the grade's full 100mm/s-plus speed range.
None of the three product pages gives a maximum Bowden tube length in millimeters — the guidance stays qualitative (shorter gap, easier print), not a number to check your printer against. If you don't know which type you have: a direct-drive printer has its extruder motor mounted right at the hotend, on the toolhead; a Bowden printer's motor sits elsewhere on the frame and pushes filament through a tube to reach the hotend. Check your printer's own spec page or manual to be sure.
The feed gate that comes first: nozzle and AMS
Nozzle choice matters separately from the AMS question above. Bambu's compatibility table, checked 2026-09-23, lists TPU 90A and TPU 85A as Not Recommended or Not Compatible on the 0.4mm, 0.6mm, and 0.8mm High Flow nozzles; its TPU 95A HF and 'TPU for AMS' filaments are Compatible across those same sizes. All four work on Bambu's standard 0.4mm, 0.6mm, and 0.8mm nozzles, at 200–250°C. Bambu's table has no plain, non-HF 95A row — a straight 95A spool from another brand on a High Flow nozzle isn't directly documented there; check with Bambu support or your nozzle's own paperwork first.
On the AMS specifically, Bambu's compatibility table lists plain 'TPU' as Compatible with an open-frame or enclosed printer feeding from outside the AMS, but Not Compatible with the AMS or AMS lite itself. Its AMS notes separately name TPU at 95A, 85A, 83A and 80A, among other soft or absorbent materials, as too soft to pass smoothly through the AMS channel. Ordering a harder-sounding number isn't a documented workaround for AMS feeding — the blanket guidance is to keep TPU out of the AMS, full stop.
Why flexible prints run slow, whichever grade you pick
| Material | Typical max volumetric speed |
|---|---|
| TPU | 2–5 mm³/s |
| PC | 6–10 mm³/s |
| PA (Nylon) | 8–12 mm³/s |
| PETG | 8–15 mm³/s |
| ABS/ASA | 10–16 mm³/s |
| PLA | 12–20 mm³/s |
That's Prusa's own knowledge base, not a TPU-specific page — it's the fastest rate, in cubic millimeters per second, that Prusa says a hotend can reliably melt filament, by material. TPU sits at the bottom regardless of Shore hardness; Prusa's stated reason is that flexible filaments require very low flow. Even PC, the next most restrictive material in that table, allows a minimum of 6 mm³/s — above TPU's top end. Expect any TPU print on this page, at any grade, to take meaningfully longer than the same part in PLA or PETG.
Matching the grade to the part
- Seals, gaskets, sockets, anything that compresses and springs back: TPU90 has the highest elongation at break of the three (592.1%) and the lowest resistance to stretching (7.1 MPa at 100% strain). It needs a direct-drive extruder and isn't recommended on Bambu's High Flow nozzles.
- Snap-fits, grips, or wearables that must hold a shape under load: TPU95 or TPU95-HF resist deforming more (11.1 and 15.5 MPa at 100% strain) while still stretching 495–551% before breaking.
- Fastest print and the broadest hardware fit: TPU95-HF prints across the widest speed range of the three, 30 to 100mm/s. Polymaker's FAQ says it's designed to print fast on direct, geared extruders and can still print on a Bowden setup. It's also the only one of the three listed Compatible on Bambu's High Flow nozzles.
- A part that also has to survive heat, like a hot car: Shore hardness doesn't answer that. Bambu's chart rates TPU's heat-deflection temperature at 1 of 5 stars, the lowest shown, and impact resistance at 5 of 5, the highest. Check the heat figure on the datasheet separately — see Choose Filament by What the Part Must Survive for which figure governs which failure.
Before you order
- Confirm your printer's extruder type, direct drive or Bowden, against Polymaker's per-grade guidance above.
- If you're on a Bambu printer, confirm your nozzle (standard or High Flow) against Bambu's table, and plan to feed TPU from outside the AMS regardless of grade.
- All three grades share the same drying setting, 70°C for 8 hours, so the grade you pick doesn't change what your dryer needs to reach. See Will Your Dryer Reach the Temperature Your Filament Needs? to check your own equipment against that number.
- For a broader, five-point compatibility check beyond TPU specifically, see Will Your Printer Run This Filament? Five Checks.
Check it on your own equipment
These take you to the manufacturers and standards bodies the page draws on, so you can look up your exact model.
- Manufacturer specification
Bambu's filament compatibility guide (nozzle and AMS table) (opens in a new tab)The nozzle-by-nozzle compatibility rows for TPU 90A, TPU 85A, TPU 95A HF, and 'TPU for AMS' on Bambu's standard and High Flow nozzles, plus the AMS/AMS-lite section's separate 'TPU: Not Compatible' note, and TPU's recommended nozzle temperature and drying settings. — wiki.bambulab.com - Manufacturer specification
Polymaker PolyFlex TPU95 product page (opens in a new tab)Polymaker's direct-drive-versus-Bowden guidance and recommended print settings for the 95A grade. — wiki.polymaker.com - Manufacturer specification
Polymaker PolyFlex TPU95-HF product page (opens in a new tab)The high-flow grade's Bowden-compatible print tips and its 30–100 mm/s speed range. — wiki.polymaker.com - Official support page
Prusa's max volumetric speed article (opens in a new tab)Why TPU's 2–5 mm³/s throughput limit is the lowest of any listed material, and how it compares to PLA, PETG, ABS/ASA, PA, and PC. — help.prusa3d.com
What this page does not tell you
- Bambu's nozzle and AMS compatibility tables can change; the figures on this page reflect what was published as of September 23, 2026 — check the live table for your exact printer and nozzle before ordering.
- Bambu's table names four TPU types (TPU for AMS, TPU 95A HF, TPU 85A, TPU 90A); it has no plain, non-HF 95A row, so a straight 95A spool from another brand isn't explicitly covered for Bambu's High Flow nozzles.
- Shore hardness measures resistance to indentation, not heat resistance or fatigue life under repeated flexing — check those figures separately for a part that also has to survive heat or years of bending.
- Polymaker's Bowden-versus-direct-drive guidance is qualitative; none of the three product pages gives a maximum tube length in millimeters, or a stated mechanical reason why the HF grade tolerates Bowden better than the other two.
Sources
11 documents, each with the facts on this page it supports. Manufacturers revise specifications, so every source is dated — open it before you buy.
- PolyFlex TPU90 has a Shore hardness of 90A, density of 1.12 g/cm³ at 23°C, stress at 100% strain of 7.1 ± 0.3 MPa, elongation at break of 592.1 ± 32.9%, a recommended printing speed of 30–70 mm/s, and a drying setting of 70°C for 8 hours.
- PolyFlex TPU95 has a Shore hardness of 95A, density of 1.20–1.24 g/cm³ at 23°C, stress at 100% strain of 11.1 ± 0.3 MPa, elongation at break of 551.2 ± 23.5%, a recommended printing speed of 30–50 mm/s, and a drying setting of 70°C for 8 hours.
- PolyFlex TPU95-HF has a Shore hardness of 95A, density of 1.16 g/cm³ at 23°C, stress at 100% strain of 15.5 ± 0.7 MPa, elongation at break of 495.8 ± 16.2%, a recommended printing speed of 30–100 mm/s, and a drying setting of 70°C for 8 hours.
- Comparing Polymaker's own published figures, stress at 100% strain more than doubles between TPU90 and TPU95-HF (7.1 MPa to 15.5 MPa) even though the Shore rating only moves from 90A to roughly 98A.
- Polymaker states that PolyFlex TPU95-HF's actual hardness measures closer to a Shore rating of 98A than to 95A.
- Polymaker says PolyFlex TPU95-HF can be printed on an indirect (Bowden) drive printer and is designed to print fast on direct, geared extruders while still printing on a Bowden setup, though direct drive is still recommended to reach its full high-speed settings.
- Polymaker says PolyFlex TPU90 should be printed on a direct-drive extruder, not a Bowden setup, because a larger gap between the extruder and hotend makes the material harder to feed.
- None of Polymaker's three PolyFlex TPU product pages publishes a specific maximum Bowden-tube length in millimeters; the extruder-gap guidance on each is qualitative only.
- Polymaker says PolyFlex TPU95 can be printed on most printers but prints faster on a direct-drive extruder than on a Bowden setup, and its FAQ still recommends a direct-drive printer.
- Shore hardness is measured by a spring-loaded indenter pressed into the material on a 0–100 scale, where 0 corresponds to a 2.54mm indentation and 100 to no penetration; Shore A uses a truncated-cone indenter under about 8.05 N of force, and Shore D uses a sharper conical indenter under about 44.5 N.
- On the Shore A scale, a comparison table on Wikipedia's Shore durometer page lists automotive tire tread at about 70A and the hard wheels on roller skates or a skateboard at about 98A.
- Shore A's practical measurement range is about 10 to 90 (usable below about 20 on the Shore D scale); Shore D's range is about 30 to 90, and becomes the appropriate scale above about 90 Shore A.
- Bambu Lab's AMS guidance says to avoid using the AMS to print flexible materials, including TPU, TPE, or absorbent PVA, because they may get stuck inside the AMS feed tube during printing.
- Bambu's filament compatibility table lists TPU as Compatible with an open-frame or enclosed printer (fed from outside the AMS) but Not Compatible with the AMS or AMS lite.
- The same Bambu page separately names TPU at 95A, 85A, 83A, and 80A, among other soft or absorbent materials, as too soft to pass smoothly through the AMS/AMS lite channel.
- Bambu's nozzle compatibility table lists its TPU 90A and TPU 85A filaments as Not Recommended or Not Compatible on the 0.4mm, 0.6mm, and 0.8mm High Flow nozzles, while its TPU 95A HF and 'TPU for AMS' filaments are listed Compatible on those same High Flow nozzle sizes; all four are listed Compatible on Bambu's standard 0.4mm, 0.6mm, and 0.8mm nozzles, at a nozzle temperature of 200–250°C.
- Bambu's own material-property chart rates TPU's heat deflection temperature level at 1 of 5 stars, the lowest rating shown in that chart, and its impact resistance at 5 of 5 stars, the highest rating shown.
- Prusa's own knowledge base lists TPU's typical max volumetric speed (MVS) at 2–5 mm³/s, described as needing 'very low flow,' the lowest range of any material in Prusa's table.
- Prusa's same table lists typical MVS ranges of 12–20 mm³/s for PLA, 8–15 mm³/s for PETG, 10–16 mm³/s for ABS/ASA, 8–12 mm³/s for PA (Nylon), and 6–10 mm³/s for PC.