EPDM A70
Hardness band
also Ethylene Propylene Diene Monomer, Nordel
A70 = shore A 70
Industry-default hardness for O-rings and dynamic-pressure static seals.
Values for the A70 condition
Other EPDM grades and fills
EPDM is listed in 12 conditions; see the grade overview at EPDM.
Compare all 12 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Closed-cell / open-cell cellular EPDM | Pick for low-closure-force dust, water and acoustic sealing (cabinet gaskets, door seals) where compression load must stay low. | — | 2 | 200 | 20 Shore A |
Shore A 40 | Soft grade for low-force conformal sealing on rough or uneven flanges. | — | 8 | 550 | 40 Shore A |
Flame-retardant | Use for rail, cable-accessory and enclosure seals needing UL 94 V-0 or EN 45545 fire performance; ATH loading raises stiffness and cuts elongation. | — | 8 | 250 | 25 Shore D |
Shore A 50 | Compromise durometer for low-pressure static gaskets needing good conformability. | — | 9 | 500 | 50 Shore A |
Carbon-black conductive / semiconductive grade | Highly conductive-black loaded compound for cable semicon layers, EMI/static-dissipative gaskets and grounding pads. | — | 10 | 250 | 25 Shore D |
Shore A 60 | General sheet/extrusion durometer balancing sealing force and abrasion life. | — | 11 | 450 | 60 Shore A |
SolidDefault Dense vulcanized EPDM compound | Default dense rubber for O-rings, gaskets, weatherstrip and hose where a pressure-tight, load-bearing seal is needed. | — | 12 | 400 | 22 Shore D |
A70This page Shore A 70 | Industry-default hardness for O-rings and dynamic-pressure static seals. | — | 12 | 400 | 22 Shore D |
Sulfur-cured | Lowest-cost, fastest-curing option for weatherstrip, roofing and general gaskets below ~120 °C. | — | 12 | 420 | 22 Shore D |
Shore A 80 | Use for higher-pressure seals, backup rings and extrusion-resistant profiles. | — | 14 | 300 | 30 Shore D |
Peroxide-cured | Choose for steam, hot water and 150 °C air service, and wherever low compression set or non-staining/low-extractable behaviour is required. | — | 15 | 350 | 22 Shore D |
Shore A 90 | Rigid rubber for bushings, wheel treads and highly extruded seal geometries. | — | 16 | 200 | 38 Shore D |
What is EPDM A70?
EPDM A70 is EPDM heat treated to A70 — industry-default hardness for O-rings and dynamic-pressure static seals. EPDM A70 has a tensile strength of 12 MPa (1.74 ksi), weaker than 76% of polymer grades. Elongation at break is 400% and the elastic modulus is 0.01 GPa (8.7×10⁻⁴ Msi). EPDM A70 has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -55°C (-67 °F). Solid is the default condition FabDigit quotes; A70 is available on request or by drawing note.
Advantages
- Good UV / weathering resistance — 95/100, better than 95% of polymer grades
- Forms and bends easily — 90/100, better than 91% of polymer grades
- Ductile — tolerates forming and impact — 400%, better than 86% of polymer grades
- Conducts heat well — 0.3 W/m·K (0.173 BTU/hr·ft·°F), better than 83% of polymer grades
Limitations
- Hard to polish — 20/100, worse than 95% of polymer grades
- High mold shrinkage — 2.5%, worse than 93% of polymer grades
- Difficult to machine — 30/100, worse than 87% of polymer grades
- Low stiffness — 0.01 GPa (8.7×10⁻⁴ Msi), worse than 86% of polymer grades
- Difficult to weld — 15/100, worse than 78% of polymer grades
EPDM A70 properties
Typical room-temperature values for EPDM A70; 16 are specific to this condition. Other listed values are EPDM reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
EPDM A70 has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -55°C (-67 °F).
Mechanical10
EPDM A70 has a tensile strength of 12 MPa (1.74 ksi), weaker than 76% of polymer grades. Elongation at break is 400% and the elastic modulus is 0.01 GPa (8.7×10⁻⁴ Msi).
Thermal8
EPDM A70 is rated for continuous service to 120°C (248 °F). It conducts heat at 0.3 W/m·K (0.173 BTU/hr·ft·°F), better than 83% of polymer grades. Thermal expansion is 180 µm/m·K (100 µin/in·°F).
Electrical6
EPDM A70 is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of EPDM A70 takes about 95 MJ of energy and emits 4 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 5%.
Manufacturability7
EPDM A70's machinability is poor (30/100, worse than 87% of polymer grades); weldability poor (15/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with EPDM A70
Is EPDM easy to machine?
Best die-cut, waterjet or knife/CNC-blade cut with soap lubricant; milling and drilling smear and tear unless the part is frozen or a sharp hollow punch is used.
Can EPDM be welded?
Not thermally weldable — join by hot vulcanized splice, uncured tape splice, or cyanoacrylate/CR contact adhesive after abrasion plus primer.
Can EPDM be formed, bent or molded?
Mix on internal mixer/two-roll mill, then extrude profiles or compression/transfer/injection mold and vulcanize ~160–200 °C; sponge grades use chemical blowing agents with a matched slow cure.
What surface finishes work on EPDM?
Surface finish comes from the mold or extrusion die; flash removed by cryogenic deflashing, and paintability/bondability requires corona, plasma or chlorination pretreatment.
EPDM 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 |
|---|---|---|
| ethylene (C2 units)polymer C2 content; high-C2 grades are semi-crystalline | 45 – 75 | 60 |
| ENB diene (5-ethylidene-2-norbornene)cure site for sulfur vulcanization; DCPD/VNB used in some grades | 0.5 – 12 | 5 |
| carbon black (N550/N660)phr on polymer, in the compounded rubber | 20 – 90 | 60 |
| paraffinic process oilphr; oil-extended polymers supplied pre-oiled | 10 – 100 | 50 |
| calcium carbonate / clay fillerphr, cost filler | 0 – 80 | 30 |
| zinc oxide + stearic acidphr, activators | ≈ 6 | 6 |
| sulfur + accelerators or organic peroxidphr, cure system | 1 – 8 | 3 |
| propylene (C3 units)balance of polymer backbone | ≥ 20 (balance) | — |
EPDM A70 — frequently asked
What is EPDM A70 used for?
EPDM A70 is typically used for automotive window and door weatherstrip, roofing membranes, steam and hot-water gaskets, coolant and radiator hoses, sponge sealing profiles for enclosures and HVAC duct and access-panel gaskets. In short: weatherproof rubber.
What is the tensile strength of EPDM A70?
EPDM A70 has a typical tensile strength of 12 MPa (1.74 ksi) — weaker than 76% of polymer grades. Strength varies by condition: see the 12 listed tempers.
Is EPDM A70 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 87% of polymer grades). Best die-cut, waterjet or knife/CNC-blade cut with soap lubricant; milling and drilling smear and tear unless the part is frozen or a sharp hollow punch is used.
Can EPDM A70 be welded?
Not readily — weldability is rated poor (15/100). Not thermally weldable — join by hot vulcanized splice, uncured tape splice, or cyanoacrylate/CR contact adhesive after abrasion plus primer.
What surface finishes work on EPDM A70?
Surface finish comes from the mold or extrusion die; flash removed by cryogenic deflashing, and paintability/bondability requires corona, plasma or chlorination pretreatment.
Can EPDM A70 be formed, bent or molded?
Mix on internal mixer/two-roll mill, then extrude profiles or compression/transfer/injection mold and vulcanize ~160–200 °C; sponge grades use chemical blowing agents with a matched slow cure.
What is the maximum service temperature of EPDM A70?
EPDM A70 is rated for continuous use to about 120°C (248 °F), and briefly to 160°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in EPDM A70?
Yes — EPDM A70 is available for injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D2000 — Rubber Products in Automotive Applications (classification AA/BA/CA/DA lines) — ASTM (2023)
- ASTM D1418 — Rubber and Rubber Latices Nomenclature (EPDM) — ASTM (2022)
- Vistalon EPDM grade and compound data — ExxonMobil Chemical (2023)
- Nordel IP EPDM technical information — Dow (2022)
- Keltan EPDM compounding guides — Arlanxeo (2023)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics/Elastomers — ASM International (1988)
- O-ring and elastomer chemical compatibility / property tables — Parker Hannifin O-Ring Handbook (2021)
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.