EPDM vs EPM
Polymer · grade comparison
EPDM and EPM are both polymer grades. EPM is the stronger of the two: tensile strength 14 MPa (2.03 ksi) against 12 MPa (1.74 ksi) for EPDM, about 17% more. In exchange, EPDM is the more ductile: elongation 400% versus 320% for EPM. EPM runs hotter in service (150°C vs 120°C continuous) and EPDM conducts heat better (0.3 W/m·K vs 0.25 W/m·K).
EPDMChoose it when the part is bent, formed or impact-loaded.
EPMChoose it when strength drives the design, or when the part sees heat.
EPDM vs EPM: 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.
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Hardness, Shore D
Tear Strength
Compression Set (22 h, 70 °C)
Same in both: Elastic (Young's) Modulus 0.01 GPa8.7×10⁻⁴ Msi · Shear Modulus 0 GPa2.9×10⁻⁴ Msi · Bulk Modulus 2 GPa0.29 Msi · Hardness, Shore A 70 Shore A
Physical
Density and transition temperatures.
Density
Water Absorption (24 h)
Same in both: Glass Transition (Tg) -55°C-67 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Max Service Temperature (short-term)
Same in both: Specific Heat Capacity 2,000 J/kg·K0.48 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 180 µm/m·K100 µin/in·°F · Min Service Temperature -50°C-58 °F · Limiting Oxygen Index 19%
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Comparative Tracking Index (CTI)
Same in both: Dielectric Strength 25 kV/mm635 V/mil
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
Formability (cold)
Polishability
Processing Melt Temperature (typ.)
Same in both: Machinability 30 / 100 · Mold Shrinkage 2.5% · Mold Temperature (typ.) 175°C347 °F
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 95 MJ/kg40,843 BTU/lb
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Same in both: Specific Stiffness (E / density) 0 MN·m/kg · Thermal Diffusivity 0.1 mm²/s · Thermal Shock Resistance Index 3
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 | EPM |
|---|---|---|
| Injection molding | Yes | — |
| Default condition | Solid | — |
| Relative cost | $$ Standard | $$ Standard |
| 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 EPM — frequently asked
Is EPM stronger than EPDM?
Yes. EPM has a typical tensile strength of 14 MPa (2.03 ksi) against 12 MPa (1.74 ksi) for EPDM — about 17% more.
Which is cheaper, EPDM or EPM?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose EPDM over EPM?
Pick EPDM when the part is bent, formed or impact-loaded. Pick EPM 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 EPM 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.