Silicone vs XNBR
Polymer · grade comparison
Silicone and XNBR are both polymer grades. XNBR is the stronger of the two: tensile strength 25 MPa (3.63 ksi) against 8 MPa (1.16 ksi) for Silicone, about 3.1 times as much. In exchange, Silicone is the more ductile: elongation 500% versus 450% for XNBR. Silicone is lighter (1.15 g/cm³ vs 1.22 g/cm³ for XNBR) and XNBR is stiffer (0.01 GPa vs 0 GPa). On the shop floor, XNBR machines more easily (fair vs poor).
SiliconeChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
XNBRChoose it when strength drives the design, or when the part is machined in volume.
Silicone vs XNBR: 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
Hardness, Shore A
Tear Strength
Compression Set (22 h, 70 °C)
Shear Strength
Hardness, Shore D
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Refractive Index
Light Transmission
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
Surface 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.
Machinability
Weldability
Formability (cold)
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 110 MJ/kg47,292 BTU/lb
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 | Silicone | XNBR |
|---|---|---|
| Injection molding | Yes | — |
| Default condition | Medical Grade | — |
| Relative cost | $$$ Premium | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | Yes | — |
| EMI Shielding Coating | Yes | — |
| Soft Touch Coating | Yes | — |
| Spray Painting | Yes | — |
| UV Coating | Yes | — |
Silicone vs XNBR — frequently asked
Is XNBR stronger than Silicone?
Yes. XNBR has a typical tensile strength of 25 MPa (3.63 ksi) against 8 MPa (1.16 ksi) for Silicone — about 3.1 times as much.
Which is cheaper, Silicone or XNBR?
Both sit in the same relative cost tier ($$$, premium); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Silicone or XNBR?
XNBR. Its machinability rates fair (35/100) against poor (20/100) for Silicone; for welding the order is Silicone first (poor, 20/100) then XNBR (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Silicone and XNBR 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.