BIIR vs EPDM
Polymer · grade comparison
BIIR and EPDM are both polymer grades. EPDM is the stronger of the two: tensile strength 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for BIIR, about 9% more. In exchange, BIIR is the more ductile: elongation 500% versus 400% for EPDM, and EPDM is harder (22 Shore D vs 15 Shore D). EPDM is stiffer (0.01 GPa vs 0 GPa) and EPDM conducts heat better (0.3 W/m·K vs 0.22 W/m·K). On the shop floor, BIIR welds better (25 vs 15 out of 100).
BIIRChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
EPDMChoose it when strength drives the design.
BIIR 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
Shear Modulus
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Hardness, Shore A
Hardness, Shore D
Tear Strength
Compression Set (22 h, 70 °C)
Same in both: Bulk Modulus 2 GPa0.29 Msi · Poisson's Ratio 0.5
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Refractive Index
Same in both: Water Absorption (24 h) 0.5%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Same in both: Thermal Expansion (CTE, 20–100 °C) 180 µm/m·K100 µin/in·°F
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).
UV / Weathering Resistance
Same in both: Corrosion Resistance 85 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Weldability
Formability (cold)
Mold Shrinkage
Mold Temperature (typ.)
Polishability
Processing Melt Temperature (typ.)
Same in both: Machinability 30 / 100
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.
Same in both: Specific Strength (UTS / density) 10 kN·m/kg · 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 | BIIR | 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 |
BIIR vs EPDM — frequently asked
Is EPDM stronger than BIIR?
Yes. EPDM has a typical tensile strength of 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for BIIR — about 9% more.
Which is cheaper, BIIR 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.
Which welds better, BIIR or EPDM?
BIIR. Its weldability rates poor (25/100) against poor (15/100) for EPDM.
Ready to make it?
Upload a CAD file and FabDigit prices the part in BIIR 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.