EPM vs Silicone
Polymer · grade comparison
EPM and Silicone are both polymer grades. EPM is the stronger of the two: tensile strength 14 MPa (2.03 ksi) against 8 MPa (1.16 ksi) for Silicone, about 75% more. In exchange, Silicone is the more ductile: elongation 500% versus 320% for EPM. EPM is stiffer (0.01 GPa vs 0 GPa) and Silicone runs hotter in service (200°C vs 150°C continuous). On the shop floor, EPM machines more easily (30 vs 20 out of 100) and EPM sits in a lower cost tier (standard, $$) than Silicone (premium, $$$).
EPMChoose it when strength drives the design, or when the part is machined in volume.
SiliconeChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
EPM 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
Tensile Strength (Ultimate)
Elongation at Break
Hardness, Shore A
Tear Strength
Compression Set (22 h, 70 °C)
Same in both: Poisson's Ratio 0.49
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 Strength
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 · Volume Resistivity 1×10¹⁵ Ω·cm
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 97 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Mold Temperature (typ.)
Weldability
Polishability
Processing Melt Temperature (typ.)
Same in both: Mold Shrinkage 2.5%
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | EPM | 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 |
EPM vs Silicone — frequently asked
Is EPM stronger than Silicone?
Yes. EPM has a typical tensile strength of 14 MPa (2.03 ksi) against 8 MPa (1.16 ksi) for Silicone — about 75% more.
Which is cheaper, EPM or Silicone?
EPM 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, EPM or Silicone?
EPM, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for Silicone.
Ready to make it?
Upload a CAD file and FabDigit prices the part in EPM 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.