IR vs Silicone
Polymer · grade comparison
IR and Silicone are both polymer grades. IR is the stronger of the two: tensile strength 22 MPa (3.19 ksi) against 8 MPa (1.16 ksi) for Silicone, about 175% more. IR is the more ductile: elongation 750% versus 500% for Silicone. IR is lighter (0.93 g/cm³ vs 1.15 g/cm³ for Silicone) and Silicone is stiffer (0 GPa vs 0 GPa). On the shop floor, IR sits in a lower cost tier (standard, $$) than Silicone (premium, $$$).
IRChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
SiliconeChoose it when the part sees heat.
IR vs Silicone: 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)
Same in both: Hardness, Shore A 50 Shore A
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Refractive Index
Light Transmission
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.
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Surface Resistivity
Comparative Tracking Index (CTI)
Same in both: Electrical Resistivity 1×10¹³ Ω·m3.94×10²⁰ µΩ·in · Dielectric Strength 22 kV/mm559 V/mil · Volume Resistivity 1×10¹⁵ Ω·cm
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
Mold Shrinkage
Mold Temperature (typ.)
Weldability
Polishability
Processing Melt Temperature (typ.)
Same in both: Formability (cold) 95 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
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 | IR | Silicone |
|---|---|---|
| Injection molding | — | Yes |
| Default condition | — | Medical Grade |
| Relative cost | $$ Standard | $$$ 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 |
IR vs Silicone — frequently asked
Is IR stronger than Silicone?
Yes. IR has a typical tensile strength of 22 MPa (3.19 ksi) against 8 MPa (1.16 ksi) for Silicone — about 175% more.
Which is cheaper, IR or Silicone?
IR is the lower-cost material: it sits in the standard tier ($$) while Silicone is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, IR or Silicone?
IR, by a small margin. Both rate poor for machinability — 25/100 against 20/100 for Silicone.
Ready to make it?
Upload a CAD file and FabDigit prices the part in IR and Silicone 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.