Cast Silicone vs VMQ
Silicone · grade comparison
Cast Silicone and VMQ are both silicone grades. VMQ is the stronger of the two: tensile strength 8 MPa (1.16 ksi) against 5 MPa (0.725 ksi) for Cast Silicone, about 60% more. In exchange, Cast Silicone is the more ductile: elongation 400% versus 350% for VMQ. Cast Silicone is lighter (1.1 g/cm³ vs 1.2 g/cm³ for VMQ) and VMQ is stiffer (0.01 GPa vs 0 GPa). On the shop floor, Cast Silicone sits in a lower cost tier (standard, $$) than VMQ (premium, $$$).
Cast SiliconeChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
VMQChoose it when strength drives the design.
Cast Silicone vs VMQ: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all silicone 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 silicone 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)
Elongation at Break
Hardness, Shore A
Tear Strength
Compression Set (22 h, 70 °C)
Bulk Modulus
Hardness, Shore D
Same in both: Poisson's Ratio 0.49
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Light Transmission
Same in both: Water Absorption (24 h) 0.3% · Water Absorption (Saturation) 1% · Refractive Index 1.41
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Same in both: Specific Heat Capacity 1,300 J/kg·K0.31 BTU/lb·°F · Max Service Temperature (continuous) 200°C392 °F
Electrical
Conductivity and insulation.
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Same in both: Electrical Resistivity 1×10¹³ Ω·m3.94×10²⁰ µΩ·in · Volume Resistivity 1×10¹⁵ Ω·cm · Surface Resistivity 1×10¹⁵ Ω · Comparative Tracking Index (CTI) 600 V
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 96 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Formability (cold)
Polishability
Mold Shrinkage
Mold Temperature (typ.)
Weldability
Processing Melt Temperature (typ.)
Same in both: Machinability 25 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Same in both: Embodied Carbon (primary production) 7 kg CO₂/kg · Embodied Water 300 L/kg35.9 gal/lb · 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 silicone grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Cast Silicone | VMQ |
|---|---|---|
| Urethane casting | Yes | — |
| Default condition | Shore A 40 | — |
| Relative cost | $$ Standard | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Cast Silicone vs VMQ — frequently asked
Is VMQ stronger than Cast Silicone?
Yes. VMQ has a typical tensile strength of 8 MPa (1.16 ksi) against 5 MPa (0.725 ksi) for Cast Silicone — about 60% more.
Which is cheaper, Cast Silicone or VMQ?
Cast Silicone is the lower-cost material: it sits in the standard tier ($$) while VMQ is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose Cast Silicone over VMQ?
Pick Cast Silicone when the part is bent, formed or impact-loaded, or when weight is the constraint. Pick VMQ when strength drives the design.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Cast Silicone and VMQ 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.