FKM vs HDPE
Polymer · grade comparison
FKM and HDPE are both polymer grades, both corrosion resistant plastic. HDPE is the stronger of the two: tensile strength 28 MPa (4.06 ksi) against 12 MPa (1.74 ksi) for FKM, about 133% more. HDPE is the more ductile: elongation 600% versus 200% for FKM. HDPE is lighter (0.96 g/cm³ vs 1.82 g/cm³ for FKM) and HDPE is stiffer (1.1 GPa vs 0.01 GPa). On the shop floor, HDPE machines more easily (very good vs poor) and HDPE sits in a lower cost tier (budget, $) than FKM (standard, $$).
FKMChoose it when the part sees heat.
HDPEChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
FKM vs HDPE: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Hardness, Shore A
Tear Strength
Compression Set (22 h, 70 °C)
Shear Modulus
Bulk Modulus
Yield Strength (0.2% offset)
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Melting Temperature (Tm)
Water Absorption (Saturation)
Refractive Index
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)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Vicat Softening Point (B50)
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
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Weldability
Formability (cold)
Polishability
Melt Flow Rate
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)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
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 | FKM | HDPE |
|---|---|---|
| CNC machining | — | Yes |
| Sheet metal | — | Yes |
| Default condition | Standard | FDA Compliant |
| Relative cost | $$ Standard | $ Budget |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
| Painting | — | Yes |
Both are offered for Injection molding. They share 5 finishes: Chrome Plating (Plastic), EMI Shielding Coating, Soft Touch Coating, Spray Painting, UV Coating.
FKM vs HDPE — frequently asked
Is HDPE stronger than FKM?
Yes. HDPE has a typical tensile strength of 28 MPa (4.06 ksi) against 12 MPa (1.74 ksi) for FKM — about 133% more.
Which is cheaper, FKM or HDPE?
HDPE is the lower-cost material: it sits in the budget tier ($) while FKM is standard ($$). 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, FKM or HDPE?
HDPE. Its machinability rates very good (75/100) against poor (25/100) for FKM.
Ready to make it?
Upload a CAD file and FabDigit prices the part in FKM and HDPE 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.