EPDM vs HNBR
Polymer · grade comparison
EPDM and HNBR are both polymer grades. HNBR is the stronger of the two: tensile strength 25 MPa (3.63 ksi) against 12 MPa (1.74 ksi) for EPDM, about 108% more. In exchange, EPDM is the more ductile: elongation 400% versus 300% for HNBR. EPDM is lighter (1.15 g/cm³ vs 1.25 g/cm³ for HNBR) and HNBR is stiffer (0.01 GPa vs 0.01 GPa). On the shop floor, EPDM sits in a lower cost tier (standard, $$) than HNBR (high, $$$$).
EPDMChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
HNBRChoose it when strength drives the design, or when the part sees heat.
EPDM vs HNBR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Tear Strength
Compression Set (22 h, 70 °C)
Shear Strength
Same in both: Hardness, Shore A 70 Shore A · Hardness, Shore D 22 Shore D
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Comparative Tracking Index (CTI)
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Weldability
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Same in both: Machinability 30 / 100 · Formability (cold) 90 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 0 MN·m/kg · Thermal Diffusivity 0.1 mm²/s
Strength versus weight
Yield strength against density for every polymer grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | EPDM | HNBR |
|---|---|---|
| Injection molding | Yes | — |
| Default condition | Solid | — |
| Relative cost | $$ Standard | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | Yes | — |
| EMI Shielding Coating | Yes | — |
| Soft Touch Coating | Yes | — |
| Spray Painting | Yes | — |
| UV Coating | Yes | — |
EPDM vs HNBR — frequently asked
Is HNBR stronger than EPDM?
Yes. HNBR has a typical tensile strength of 25 MPa (3.63 ksi) against 12 MPa (1.74 ksi) for EPDM — about 108% more.
Which is cheaper, EPDM or HNBR?
EPDM is the lower-cost material: it sits in the standard tier ($$) while HNBR is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose EPDM over HNBR?
Pick EPDM when the part is bent, formed or impact-loaded, or when weight is the constraint. Pick HNBR when strength drives the design, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in EPDM and HNBR side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.