TPU · hardness band
TPU Shore A 70
Properties of the Shore A 70 condition, compared with the other TPU grades.
Pick for soft-touch overmoulds, flexible tubing, bellows and low-durometer seals.
What is TPU Shore A 70?
TPU Shore A 70 is TPU heat treated to Shore A 70 — pick for soft-touch overmoulds, flexible tubing, bellows and low-durometer seals. TPU Shore A 70 has a tensile strength of 28 MPa (4.06 ksi), weaker than 64% of polymer grades. Elongation at break is 680% and the elastic modulus is 0.01 GPa (0.0017 Msi). TPU Shore A 70 has a density of 1.13 g/cm³ (0.0408 lb/in³), lighter than 61% of polymer grades. Its glass-transition temperature is -40°C (-40 °F). Shore A 85 is the default condition FabDigit quotes; Shore A 70 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 680%, better than 95% of polymer grades
- Forms and bends easily — 90/100, better than 92% of polymer grades
- Readily welded — 85/100, better than 88% of polymer grades
Limitations
- Difficult to machine — 25/100, worse than 93% of polymer grades
- Low stiffness — 0.01 GPa (0.0017 Msi), worse than 80% of polymer grades
- Absorbs moisture — dry before molding — 0.8%, worse than 80% of polymer grades
TPU Shore A 70 properties
Typical room-temperature values for TPU Shore A 70 — 10 properties are specific to this condition; the rest are grade-level values shared by every TPU grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical6
TPU Shore A 70 has a density of 1.13 g/cm³ (0.0408 lb/in³), lighter than 61% of polymer grades. Its glass-transition temperature is -40°C (-40 °F).
Mechanical8
TPU Shore A 70 has a tensile strength of 28 MPa (4.06 ksi), weaker than 64% of polymer grades. Elongation at break is 680% and the elastic modulus is 0.01 GPa (0.0017 Msi).
Thermal9
TPU Shore A 70 is rated for continuous service to 75°C (167 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 170 µm/m·K (94.4 µin/in·°F).
Electrical7
TPU Shore A 70 is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 64% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of TPU Shore A 70 takes about 105 MJ of energy and emits 5.2 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 2%.
Manufacturability8
TPU Shore A 70's machinability is poor (25/100, worse than 93% of polymer grades); weldability excellent (85/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other TPU grades and fills
TPU is also supplied in 13 other conditions. The full side-by-side table is on the TPU overview.
- Shore A 85DefaultDefault all-round hardness for seals, cable jackets, wheels, grips and flexible parts.40 MPa tensile
- Shore A 95Pick for load-bearing rollers, couplings, ski boots, hose and abrasion-critical parts needing stiffness with flexibility.50 MPa tensile
- GF20Use where a semi-rigid, dimensionally stable structural part with TPU toughness is needed (housings, wheel hubs, sports hardware).45 MPa tensile
- Shore A 60 to Shore D 80Use when the design tolerates any TPU hardness and the exact grade is chosen later by the moulder.40 MPa tensile
- As PrintedUse for printed flexible prototypes, gaskets and shoe midsoles; expect 60–80 % of injection-moulded strength and Z-direction weakness.28 MPa tensile
- Shore A 70Pick for soft-touch overmoulds, flexible tubing, bellows and low-durometer seals.28 MPa tensile
- Shore D 60Choose for stiff snap-fit housings, wheel cores, chain guides and cable strain relief that must still absorb impact at low temperature.25 MPa yield · 60 Shore D
Working with TPU Shore A 70
Is TPU easy to machine?
Machinable but gummy — use very sharp single-flute or polished carbide tools, high speed with low feed, air blast or chilling; harder D-grades cut far better than soft A-grades.
Can TPU be welded?
Readily joined by hot-air, hot-plate, ultrasonic, RF/high-frequency and laser welding; also solvent bondable with THF/DMF and cyanoacrylate/PU adhesives.
Can TPU be formed, bent or molded?
Dry pellets 2–4 h at 80–110 °C to <0.02 % moisture, melt 195–235 °C, mould 20–50 °C, generous gates and slow-then-fast fill; extrudes and thermoforms well, shrinkage 0.5–1.8 %.
What surface finishes work on TPU?
Takes flexible PU paints and pad/screen printing after flame or plasma pretreatment; not platable or polishable in the metal sense — surface texture is set by mould or print parameters.
TPU chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| MDI (4,4'-diphenylmethane diisocyanate) aromatic; HDI/H12MDI in aliphatic grades | 20 – 45 | 30 |
| 1,4-butanediol chain extender | 4 – 12 | 8 |
| processing aids / waxes / antioxidants | 0.2 – 2 | 0.8 |
| glass fiberreinforced grades only | 0 – 30 | 0 |
| flame retardant (halogen-free phosphorusFR V-0 grades only | 0 – 20 | 0 |
| polyol soft segment (polyester adipate odefines ester vs ether family | ≥ 45 (balance) | — |
TPU Shore A 70 — frequently asked
What is TPU Shore A 70 used for?
TPU Shore A 70 is typically used for caster and skate wheels, hydraulic and pneumatic seals, drive and timing belts, cable jacketing and strain reliefs, protective phone and device cases and inflatable boat fabrics. In short: tough flexible elastic.
What is the tensile strength of TPU Shore A 70?
TPU Shore A 70 has a typical tensile strength of 28 MPa (4.06 ksi) — weaker than 64% of polymer grades. Strength varies by condition: see the 14 listed tempers.
Is TPU Shore A 70 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of polymer grades). Machinable but gummy — use very sharp single-flute or polished carbide tools, high speed with low feed, air blast or chilling; harder D-grades cut far better than soft A-grades.
Can TPU Shore A 70 be welded?
Yes — weldability is rated excellent (85/100). Readily joined by hot-air, hot-plate, ultrasonic, RF/high-frequency and laser welding; also solvent bondable with THF/DMF and cyanoacrylate/PU adhesives.
What surface finishes work on TPU Shore A 70?
Takes flexible PU paints and pad/screen printing after flame or plasma pretreatment; not platable or polishable in the metal sense — surface texture is set by mould or print parameters.
Can TPU Shore A 70 be formed, bent or molded?
Dry pellets 2–4 h at 80–110 °C to <0.02 % moisture, melt 195–235 °C, mould 20–50 °C, generous gates and slow-then-fast fill; extrudes and thermoforms well, shrinkage 0.5–1.8 %.
What is the maximum service temperature of TPU Shore A 70?
TPU Shore A 70 is rated for continuous use to about 75°C (167 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in TPU Shore A 70?
Yes — TPU Shore A 70 is available for CNC machining, sheet metal, injection molding and 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Elastollan Material Properties (TPU) brochure — BASF Polyurethanes (2023)
- Pellethane TPU product selection guide — Lubrizol Engineered Polymers (2022)
- Texin / Desmopan TPU datasheets — Covestro (2023)
- CAMPUS plastics database — TPU (ISO 10350 datasheets) — CAMPUS Consortium (2024)
- ISO 868 / ISO 37 / ISO 34-1 / ISO 815 elastomer test methods — ISO (2019)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.