FEPM vs FFKM
Polymer · grade comparison
FEPM and FFKM are both polymer grades. FFKM is the stronger of the two: tensile strength 17 MPa (2.47 ksi) against 16 MPa (2.32 ksi) for FEPM, about 6% more. In exchange, FEPM is the more ductile: elongation 250% versus 140% for FFKM. FEPM is lighter (1.55 g/cm³ vs 2 g/cm³ for FFKM) and FFKM is stiffer (0.01 GPa vs 0.01 GPa). On the shop floor, FFKM sits in a lower cost tier (standard, $$) than FEPM (high, $$$$).
FEPMChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
FFKMChoose it when strength drives the design, or when the part sees heat.
FEPM vs FFKM: 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
Tensile Strength (Ultimate)
Elongation at Break
Hardness, Shore A
Hardness, Shore D
Tear Strength
Compression Set (22 h, 70 °C)
Shear Strength
Same in both: Poisson's Ratio 0.49
Physical
Density and transition temperatures.
Density
Water Absorption (24 h)
Same in both: Glass Transition (Tg) -3°C27 °F
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Same in both: Thermal Conductivity 0.22 W/m·K0.13 BTU/hr·ft·°F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 95 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Formability (cold)
Mold Shrinkage
Mold Temperature (typ.)
Same in both: Machinability 20 / 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 | FEPM | FFKM |
|---|---|---|
| Injection molding | — | Yes |
| Default condition | — | Semiconductor Grade |
| Relative cost | $$$$ High | $$ 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 |
FEPM vs FFKM — frequently asked
Is FFKM stronger than FEPM?
Yes. FFKM has a typical tensile strength of 17 MPa (2.47 ksi) against 16 MPa (2.32 ksi) for FEPM — about 6% more.
Which is cheaper, FEPM or FFKM?
FFKM is the lower-cost material: it sits in the standard tier ($$) while FEPM is high ($$$$). 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 FEPM over FFKM?
Pick FEPM when the part is bent, formed or impact-loaded, or when weight is the constraint. Pick FFKM when strength drives the design, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in FEPM and FFKM 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.