Kevlar 149 vs Nomex
Composite · grade comparison
Kevlar 149 and Nomex are both composite grades. Kevlar 149 is the stronger of the two: tensile strength 3,400 MPa (493 ksi) against 90 MPa (13.1 ksi) for Nomex, about 38 times as much. In exchange, Nomex is the more ductile: elongation 12% versus 1.5% for Kevlar 149. Nomex is lighter (1.1 g/cm³ vs 1.47 g/cm³ for Kevlar 149) and Kevlar 149 is stiffer (175 GPa vs 2.5 GPa). On the shop floor, Nomex machines more easily (fair vs poor).
Kevlar 149Choose it when strength drives the design.
NomexChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
Kevlar 149 vs Nomex: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all composite 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 composite 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Tear Strength
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
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
Same in both: Max Service Temperature (short-term) 300°C572 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Dielectric Strength
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 25 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Same in both: Embodied Water 400 L/kg47.9 gal/lb · Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every composite grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Kevlar 149 | Nomex |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Kevlar 149 vs Nomex — frequently asked
Is Kevlar 149 stronger than Nomex?
Yes. Kevlar 149 has a typical tensile strength of 3,400 MPa (493 ksi) against 90 MPa (13.1 ksi) for Nomex — about 38 times as much.
Which is cheaper, Kevlar 149 or Nomex?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Kevlar 149 or Nomex?
Nomex. Its machinability rates fair (50/100) against poor (25/100) for Kevlar 149.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Kevlar 149 and Nomex 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.