3D Printing Info

Filament comparison

e-TPU vs PA6-GF

Compare printing settings, strength, heat resistance, dated prices and sources.

Foaming / expanded TPU (TPU Aero / TPU Air) guideGlass-fibre PA6 (PA6-GF) guide

2 selected · all documented properties

Open these two in the interactive comparisonMore e-TPU comparisonsMore PA6-GF comparisons
e-TPU vs PA6-GF — documented properties and sources
PropertyFoaming / expanded TPU (TPU Aero / TPU Air)FLEXGlass-fibre PA6 (PA6-GF)PA
Market snapshot
Listing priceUSD/kg; dated snapshots$52.05/kg median; $41.99–$85.29/kg across 6 dated product listings$59.98/kg median; $39.99–$130.00/kg across 6 dated product listings
Identity & Market
Base polymer / chemistryFoaming thermoplastic polyurethane — a blowing agent expands the extrudate so the printed Shore hardness can be tuned by flow rate[1]PA6 reinforced with chopped glass fibre — Polymaker's grade is 25 wt%[2][3]
Densityg/cm³1.15 filament (Siraya Tech Flex TPU Air) and 1.05 (Roamr TPU Air HR), ISO 1183; the printed part falls to 0.51–0.93 depending on nozzle temperature (ISO 845)[4][5]1.14 (Bambu Lab) and 1.20 (Polymaker Fiberon), ISO 1183[3][2]
Typical priceUSD/kg1 kg-equivalent spools span 42–85; the middle of the market is about 52[6][7][8][9][10][11]1 kg-equivalent spools span 40–130; the middle of the market is about 60[3][12][13]
Price range across brandsUSD/kg42–85 across brands; QIDI TPU-Aero 42, Siraya Tech Flex TPU Air 45, Phaetus aeFlex TPU-Aero 49 direct and 40 at West3D, Roamr TPU Air HR 80A 55 at 800 g, Recreus Filaflex Foamy 73 at 750 g, colorFabb varioShore 85 at 700 g[6][7][8][9][10][11][14]40–130 across brands; SUNLU 40, YXPOLYER 45, Polymaker Fiberon and Bambu Lab 60, 3DXTech FibreX 87, Obsidian Nylon 6+GF 130[12][3][15][13][16]
Market availability1–5Available from several mainstream brands — colorFabb, Recreus, QIDI, Phaetus, Siraya Tech and FusRock all sell an active-foaming TPU[1][6][7][8][10][11]Stocked by most mainstream brands[3][12][15][13][16]
Spool sizes & diameters1.75 mm; 0.7, 0.75, 0.8, 1 and 3 kg spools[1][6][8][9][11]1.75 and 2.85 mm; 0.5, 0.75 and 1 kg spools[12][15][3]
Typical applicationsCushioning, midsoles, insoles and soft-touch parts where the softness needs to vary within one print; Siraya Tech's Roamr line is aimed specifically at printed footwear[1][9]Stiff, heat-resistant structural parts where a matte finish and lower cost beat carbon fibre[3][2]
Diameter tolerance± mm0.03 (Siraya Tech and Roamr, 1.75 mm)[4][5]Not documented
Printing Parameters
Nozzle temperature°C230–270 (QIDI and Siraya Tech), 220–260 (Roamr); foaming activates near 230 °C and is strongest at the top of the range[1][4][5][10]260–290 (Bambu Lab)[3]
Bed temperature°C30–45 (QIDI and Siraya Tech), 35–50 (Roamr) — a hot bed makes the foamed part over-stick[4][5][10]Not documented
Enclosure / chamber requirement1–5Open frame is fine — Roamr states no enclosure is required[1][5]Enclosure required (passive) — Bambu Lab specifies a 45–60 °C chamber[3]
Recommended chamber temperature°CNot documented45–60 (Bambu Lab)[3]
Part cooling fan100 % — cooling sets the foamed structure quickly (Siraya Tech and Roamr)[4][5]Not documented
Bed surface & adhesion aidPEI sheet or painter's tape; Polymaker warns TPU can over-stick and advises a glue stick as a release agent, and Siraya Tech recommends PVP glue or Magigoo as a release agent on PEI[17][18][4]PEI sheet with a glue stick, or a dedicated adhesive such as Magigoo[19][20]
Maximum volumetric flow (mm³/s; see test conditions)mm³/sUp to 12 (Siraya Tech, Flex TPU Air)[8]10 at Bambu Lab's 130 mm/s cap on a 0.4 mm nozzle at 0.2 mm layer[3][21]
Bed-adhesion difficulty1–5Not documentedNeeds a specific surface plus adhesive[19]
Stringing / oozing tendency1–5Severe — the material expands inside the hot end, so it oozes on travel moves; QIDI states retraction tuning cannot fix it and Siraya Tech advises setting retraction distance and speed to zero[4][10]Moderate — retraction tuning needed[20]
Overall printing difficulty1–5Advanced — enclosure, hardware upgrades, tuning; both density and hardness follow nozzle temperature and flow[1]Expert / industrial hardware only[3][22]
Extruder requirementDirect drive; the base material is a 92A TPU[1][23]0.6 mm nozzle recommended by Bambu Lab; 0.4 and 0.8 also supported[3]
Hardware Wear & Reliability
Nozzle hardness required1–4Brass fine indefinitely — Roamr states plainly that no hardened nozzle is needed[24][5]Hardened steel required — Polymaker measures brass nozzle life at about 9 h on PA6-GF25 and recommends hardened steel or ruby[2]
Abrasiveness1–5Non-abrasive[24]Highly abrasive — standard GF composite; Polymaker puts brass nozzle life at roughly 9 h on PA6-GF25[2]
Nozzle clog risk1–5Not documentedVery high — frequent jams without careful setup[22]
Heat-creep / jam sensitivity1–5Not documentedModerate — good heatbreak cooling needed[19]
Hotend requirementNo special hot-end required, but a direct-drive extruder is (Simplify3D)[17]May require an all-metal hot end (Simplify3D)[19]
Moisture Behaviour
Moisture absorption (hygroscopicity)1–5Moderate[22]Very high (>2 %) — 2.56 % saturated at 25 °C / 55 % RH (Bambu Lab) and 3.33 % equilibrium (Polymaker Fiberon), the highest in the dataset[3][2]
Equilibrium moisture content at ~50 % RH%1.09 water absorption (QIDI TPU-Aero; the standard is not stated)[10]2.56 saturated at 25 °C / 55 % RH (Bambu Lab); 3.33 equilibrium (Polymaker Fiberon PA6-GF25)[3][2]
Drying temperature & time70–80 °C for 4–6 h; keep below 15 % RH while printing (Siraya Tech, Roamr and QIDI)[4][5][10]80 °C for 8–12 h (Bambu Lab)[3]
Symptoms when wetBubbling and popping at the nozzle, stringing and a rough surface; Siraya Tech adds that moisture wrecks the foaming itself, not only the surface[22][4]Popping and cracking during extrusion, then hard-to-diagnose defects[25]
Effect of moisture on strengthPolymaker groups TPU with the highly hygroscopic materials; no dry-versus-conditioned figures are published[22]Polymaker publishes dry and wet printed blocks for PA6-GF25 itself: at 4.57 % moisture tensile falls 80.1 → 40.2 MPa and modulus 5357 → 1794 MPa, while notched Charpy rises 10.0 → 28.0 kJ/m²[2][25]
Storage requirementSealed with desiccant; often kept in a dryer during the print[22]Sealed below 20 % RH with desiccant[22]
Hydrolysis at melt temperatureNot documentedPolymaker specifies an 80–100 °C dry and storage below 20 % RH; no molecular-weight loss figure is published, and the wet data it does publish is conditioning rather than melt hydrolysis[26][27]
Mechanical Properties
Tensile strength (XY)MPaFalls with foaming: colorFabb 24 unfoamed and 12 foamed (ISO 527-1A); Siraya Tech 10.3 at break printed at 240 °C down to 3.8 at 270 °C; QIDI 6.81 at break (ISO 527, XY)[1][4][10]75 ± 6 (Bambu Lab) and 80.1 ± 1.8 (Polymaker Fiberon, dry/annealed) printed XY, ISO 527; Fiberon falls to 40.2 ± 2.1 conditioned to 4.57 % moisture. Stratasys FDM PA6/66-GF30-FR gives 60.2-61.1 at break and 61.7-62.3 at yield printed XZ (ASTM D638)[3][2][28]
Young's modulusMPa50 unfoamed and 40 foamed (colorFabb, ISO 527-1A)[1]2850 ± 260 (Bambu Lab) and 5357 ± 211 (Polymaker Fiberon, dry) printed XY, ISO 527; Fiberon falls to 1794 ± 84 conditioned. Stratasys FDM PA6/66-GF30-FR gives 5600-5830 printed XZ against 3050-3140 in ZX (ASTM D638)[3][2][28]
Elongation at break%465 unfoamed and 450 foamed (colorFabb, ISO 527-1A); Siraya Tech 629 at 240 °C down to 475 at 270 °C; Roamr 760 down to 540; QIDI 576 (ISO 527, XY)[1][4][5][10]2.4 ± 0.2 dry (Polymaker Fiberon) to 3.9 ± 0.8 (Bambu Lab) printed XY, ISO 527; the Fiberon grade rises to 4.2 ± 0.7 conditioned[3][2]
Flexural modulusMPa50 unfoamed and 40 foamed flexural modulus (colorFabb, ISO 178)[1]3670 ± 140 printed XY, ISO 178 (Bambu Lab)[3]
Charpy impact, notchedkJ/m²Not documented10.0 ± 0.7 printed XY dry and 28.0 ± 1.0 conditioned, ISO 179 notched (Polymaker Fiberon); Bambu Lab 7.2 ± 2.3[2][3]
Other impact dataNot documentedCharpy unnotched 27.2 ± 2.2 printed XY (Bambu Lab, ISO 179). Stratasys FDM PA6/66-GF30-FR gives Izod notched 74.6-77.1 J/m printed XZ against 17.2-22.1 in ZX (ASTM D256)[3][28]
Layer adhesion / Z tensileMPaNot documented27 ± 5 (Bambu Lab) and 60.7 ± 1.1 (Polymaker Fiberon, dry) printed Z, ISO 527 — the two makers differ by more than a factor of two; Fiberon falls to 26.3 ± 1.5 conditioned. Stratasys FDM PA6/66-GF30-FR gives 23.7-24.4 at break printed ZX (ASTM D638)[3][2][28]
Brittleness1–5Very ductile — bends far before failing[1]Brittle — snaps with little warning; elongation at break 2.4 % in XY[2]
Hardness (scale-specific)Shore A / Shore D / RockwellTunable by nozzle temperature: colorFabb 92 Shore A unfoamed; Siraya Tech 78 A printed at 240 °C falling to 63 A at 270 °C, Roamr TPU Air HR 80A 80 A down to 66 A and HR 85A 83 A down to 70 A (ISO 7619)[1][4][5][29]Rockwell M88 / R117 on extruded PA66-GF30 stock (ASTM D785)[30]
Creep resistance / sustained load1–5Poor — no foamed-grade creep test; a printed 95A TPU bar crept from 74.5 to 82.7 mm over 5 days at 1.25 kg[31]Good. Ensinger lists high creep resistance as a headline property of extruded PA66-GF30 stock; the rating is held below Excellent because equilibrium moisture uptake of 3.33 % softens the matrix in service[30][2]
Fatigue / repeated-flex resistance1–5Excellent — living hinges viable[18]Good. Ensinger lists high fatigue strength as a headline property of extruded PA66-GF30 stock[30]
Elasticity / flexibility1–5Rubbery / highly elastic[1]Rigid[3]
Z strength as % of XY%Not documented36 (Bambu Lab) to 76 (Polymaker Fiberon), printed; Stratasys FDM PA6/66-GF30-FR gives 39-41 (ZX against XZ tensile at break, ASTM D638)[3][2][28]
Thermal Properties
HDT at 0.45 MPa°CNot documented182 (Bambu Lab) and 191 (Polymaker Fiberon), ISO 75 at 0.45 MPa. Stratasys FDM PA6/66-GF30-FR gives 161 printed XY and 185 XZ (ASTM D648 at 66 psi)[3][2][28]
HDT at 1.8 MPa°CNot documented157 (Polymaker Fiberon) and 158 (Bambu Lab), ISO 75 at 1.8 MPa[3][2]
Glass transition (Tg)°CNot documented67 (Bambu Lab) and 70.4 (Polymaker Fiberon), DSC; Stratasys measures 51.5 on FDM PA6/66-GF30-FR (ASTM D7426)[3][2][28]
Melting point / Vicat°CVicat softening drops as the foam expands: 83 printed at 240 °C to 53 at 270 °C (Siraya Tech, ISO 306); QIDI 70.4[4][10]214.5 (Polymaker Fiberon) and 219 (Bambu Lab) melting, DSC; Vicat 210–212 (ISO 306)[3][2]
Annealing responseFoaming activates near 230 °C and expands the extrudate about 1.6×; colorFabb advises dropping flow to 60–70 % to realise the weight saving, and Siraya Tech publishes a flow schedule from 85–90 % at 230 °C down to 50–55 % at 270 °C[1][4]Not documented
Thermal expansion (CTE)µm/m·KNot documented48.6 on extruded PA66-GF30 stock (ASTM D696; source states 2.7e-5 in/in/°F). Stratasys measures much higher on printed FDM PA6/66-GF30-FR — 95.4 over -20 to 5 °C and 214 over 25 to 80 °C in XY (ASTM E831)[30][28]
Flammability / UL 94Not documentedFlammable; no UL 94 rating published for the grades surveyed[26]
Environment & Chemical
UV resistance1–5Good — years with some colour shift; Polymaker lists UV exposure among the conditions TPU withstands[18]Months outdoors before embrittlement — unstabilised polyamide yellows under UV[20]
Chemical resistanceWithstands industrial solvents and UV exposure (Polymaker)[18]Withstands oils, fuels and alkalis[20]
Water / humidity resistance in service1–5Not documentedAbsorbs water, properties shift[25]
Food contactNot food safe without specific certification (Polymaker)[18]Not food-contact certified as filament[20]
Biodegradability / compostabilityNot biodegradable[18]Not biodegradable[20]
RecyclabilityNot accepted in household plastic collection[18]Not accepted in household plastic collection[20]
Electrical & ESD propertiesNot documentedSurface resistivity above 10¹² ohm — insulating (Polymaker Fiberon, ANSI/ESD S11.11)[2]
Health & Safety
Fume toxicity1–5Low hazard — minimal VOC and particle emission; TPU was not among the nine filaments in the chamber study[32]Moderate — measurable VOCs and UFPs, ventilation advised[32]
VOC emission rateµg/minNot documentedUp to 180 caprolactam, the dominant VOC from nylon and the largest single-VOC rate in the study[32]
Ultrafine-particle emission rateparticles/minNot documented≈2 × 10⁸ median for nylon — low for particles despite the highest VOC mass measured[32]
Hazardous species emittedNot documentedCaprolactam, at up to 180 µg/min from nylon filament[32]
Ventilation / filtration requirement1–5Open a window / occasional ventilation[32]Ventilated room or enclosure recommended[32]
Dust & fibre handling hazardNot documentedGlass fibre is bound in the matrix; avoid inhaling sanding dust[2]
Post-Processing
Sanding & machiningDifficult to sand or smooth; Polymaker limits post-processing to trimming or tumbling[18]Sands poorly — gums rather than powders[19]
Gluing & solvent weldingCyanoacrylate bonds TPU; no common solvent welds it[18]Cyanoacrylate; no common solvent welds polyamide[19]
Vapour / chemical smoothingNo practical vapour smoothing[18]No practical vapour smoothing[19]
Support material pairingPolymaker warns TPU supports are often very difficult to remove[18]Not documented
Dimensional accuracy & detailFoamed surfaces are matte and textured; holding a consistent hardness means holding the nozzle temperature steady, and the printed density moves by nearly a factor of two across the 230–270 °C window[1][4]Not documented
Solvents & Solubility
Soluble inDMF, DMSO, NMP and THF dissolve TPU; acetone, MEK and cyclohexanone are partial solvents. All laboratory reagents.[33]Formic acid, phenol, m-cresol and hexafluoroisopropanol dissolve the matrix at 23 °C, leaving the fibre; laboratory reagents.[34]
Softened or crazed byToluene and benzene swell it up to +50 % by weight at 23 °C; the foamed wall soaks up esters and alcohols faster still.[33]Zinc chloride solutions stress-crack the nylon matrix, alcoholic calcium chloride dissolves it, mineral acids attack it.[34]
Solvent welding & smoothing agentNone practical — the true solvents (DMF, THF, NMP) are laboratory reagents and leave the joint swollen and weak.[33]None — nylon's only solvents (formic acid, phenol, HFIP) degrade the part, and the fibre blocks surface flow anyway.[34]

Material entries describe families or representative grades, not an interchangeable specification for every spool. Test methods, orientations and conditions may differ. Unknown values are marked “Not documented”. Prices and source dates remain historical snapshots; check the linked guide for product details. Differences highlight text, not a universal winner.

Sources for this comparison

  1. varioShore TPU Technical Data Sheet colorFabb · 2026-08 · tds
  2. Fiberon PA6-GF25 Technical Data Sheet V1.1 Polymaker · 2024-12 · tds
  3. Bambu Filament Technical Data Sheet — PA6-GF Bambu Lab · 2026-08 · tds
  4. Siraya Tech Flex TPU Air Technical Data Sheet Siraya Tech · 2026-08 · tds
  5. Roamr TPU Air HR 80A Technical Data Sheet Siraya Tech · 2026-08 · tds
  6. Recreus product catalogue Recreus · 2026-08 · vendor
  7. varioShore TPU Natural — product page colorFabb US · 2026-08 · vendor
  8. Siraya Tech Flex TPU Air Black Filament — lightweight foaming flexible, product page Siraya Tech · 2026-08 · vendor
  9. Roamr TPU Air HR 80A Filament — product page Siraya Tech · 2026-08 · vendor
  10. TPU-Aero Lightweight TPU Filament — product page with specification tables QIDI Tech · 2026-08 · vendor
  11. aeFlex TPU-Aero — active foaming low weight TPU, product page Phaetus · 2026-08 · vendor
  12. Polymaker product catalogue Polymaker · 2026-08 · vendor
  13. SUNLU Nylon-6 Glass Fiber (PA6-GF) 3D Printer Filament 1 kg — product page SUNLU · 2026-08 · vendor
  14. Phaetus aeWorthy TPU-Aero — reseller listing West3D · 2026-08 · vendor
  15. 3DXTech product catalogue 3DXTech · 2026-08 · vendor
  16. YXPOLYER PA6-GF Black 1 kg — product page YXPOLYER · 2026-08 · vendor
  17. Flexible (TPE/TPU) — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  18. TPU — material basics Polymaker Wiki · 2026-08 · doc
  19. Nylon — Ultimate 3D Printing Materials Guide Simplify3D · 2026-08 · doc
  20. PA (Nylon) — material basics Polymaker Wiki · 2026-08 · doc
  21. Max volumetric speed Prusa Knowledge Base · 2026-08 · doc
  22. Wet Filament — signs, causes and drying Polymaker Wiki · 2026-08 · doc
  23. NinjaFlex 85A Technical Specifications NinjaTek · 2026-08 · tds
  24. Extrudr Product Catalogue (DURAPRO PA12 data block) Extrudr · 2025-03 · tds
  25. Moisture Conditioning — effect on printed nylon properties Polymaker Wiki · 2026-08 · doc
  26. Fiberon PA6-CF20 Technical Data Sheet V1.1 Polymaker · 2024-12 · tds
  27. PolyMide CoPA Technical Data Sheet V5.4 (dry and wet status blocks) Polymaker · 2024-11 · tds
  28. FDM PA6/66-GF30-FR — Material Data Sheet Stratasys · 2026-07 · tds
  29. Roamr TPU Air HR 85A Technical Data Sheet Siraya Tech · 2026-08 · tds
  30. TECAMID 66 GF30 black (PA66-GF30) — stock shape properties Ensinger · 2026-08 · tds
  31. BambuLab TPU 95A HF vs Qidi TPU 95A HF — results spreadsheet My Tech Fun (Igor Gaspar) · 2024-02 · test
  32. Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop Three-Dimensional Printers with Multiple Filaments (Azimi et al.) Environmental Science & Technology 50(3) 1260-1268 · 2016-01 · paper
  33. Elastollan — Chemical properties: swelling and chemical resistance BASF · 2026-08 · tds
  34. Ultramid Nylon Chemical Resistance guide (unmodified PA6 B27E and PA66 A27E) BASF · 2026-08 · tds