CR vs EPDM
Polymer · grade comparison
CR and EPDM are both polymer grades. CR is the stronger of the two: tensile strength 17 MPa (2.47 ksi) against 12 MPa (1.74 ksi) for EPDM, about 42% more. EPDM is harder — 22 Shore D against 15 Shore D for CR — which matters for wear surfaces and threads. EPDM is lighter (1.15 g/cm³ vs 1.42 g/cm³ for CR) and EPDM is stiffer (0.01 GPa vs 0.01 GPa).
CRChoose it when strength drives the design.
EPDMChoose it when surface hardness matters, or when weight is the constraint.
CR vs EPDM: 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
Tensile Strength (Ultimate)
Hardness, Shore A
Hardness, Shore D
Tear Strength
Compression Set (22 h, 70 °C)
Shear Modulus
Bulk Modulus
Same in both: Poisson's Ratio 0.5 · Elongation at Break 400%
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
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.
Formability (cold)
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Weldability
Polishability
Same in both: Machinability 30 / 100 · Mold Shrinkage 2.5%
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 5%
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 | CR | EPDM |
|---|---|---|
| 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 |
CR vs EPDM — frequently asked
Is CR stronger than EPDM?
Yes. CR has a typical tensile strength of 17 MPa (2.47 ksi) against 12 MPa (1.74 ksi) for EPDM — about 42% more.
Which is cheaper, CR or EPDM?
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 CR over EPDM?
Pick CR when strength drives the design. Pick EPDM when surface hardness matters, or when weight is the constraint.
Ready to make it?
Upload a CAD file and FabDigit prices the part in CR and EPDM 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.