Boron Fiber Composite vs Kevlar 29
Composite · grade comparison
Boron Fiber Composite and Kevlar 29 are both composite grades. Kevlar 29 is the stronger of the two: tensile strength 2,920 MPa (424 ksi) against 1,500 MPa (218 ksi) for Boron Fiber Composite, about 95% more. Kevlar 29 is the more ductile: elongation 3.6% versus 0.75% for Boron Fiber Composite. Kevlar 29 is lighter (1.44 g/cm³ vs 2 g/cm³ for Boron Fiber Composite) and Boron Fiber Composite is stiffer (205 GPa vs 70.5 GPa). On the shop floor, Kevlar 29 machines more easily (poor vs not recommended).
Kevlar 29Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Boron Fiber Composite vs Kevlar 29: 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.
Boron Fiber CompositeKevlar 29
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
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
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
Max Service Temperature (short-term)
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
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 Temperature (typ.)
Same in both: Polishability 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)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
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 | Boron Fiber Composite | Kevlar 29 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Boron Fiber Composite vs Kevlar 29 — frequently asked
Is Kevlar 29 stronger than Boron Fiber Composite?
Yes. Kevlar 29 has a typical tensile strength of 2,920 MPa (424 ksi) against 1,500 MPa (218 ksi) for Boron Fiber Composite — about 95% more.
Which is cheaper, Boron Fiber Composite or Kevlar 29?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Boron Fiber Composite or Kevlar 29?
Kevlar 29. Its machinability rates poor (25/100) against not recommended (8/100) for Boron Fiber Composite.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Boron Fiber Composite and Kevlar 29 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.