Carbon Fiber vs Onyx
Composite · grade comparison
Carbon Fiber and Onyx are both composite grades, both high strength composite. Carbon Fiber is the stronger of the two: tensile strength 650 MPa (94.3 ksi) against 40 MPa (5.8 ksi) for Onyx, about 16 times as much. In exchange, Onyx is the more ductile: elongation 25% versus 1.2% for Carbon Fiber. Onyx is lighter (1.2 g/cm³ vs 1.55 g/cm³ for Carbon Fiber) and Carbon Fiber is stiffer (70 GPa vs 2.4 GPa). On the shop floor, Onyx machines more easily (good vs fair) and Carbon Fiber sits in a lower cost tier (premium, $$$) than Onyx (high, $$$$).
Carbon FiberChoose it when strength drives the design, or when the part sees heat.
OnyxChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
Carbon Fiber vs Onyx: 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
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Yield Strength (0.2% offset)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Melting Temperature (Tm)
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
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Max Service Temperature (short-term)
Heat Deflection Temp. @ 0.45 MPa
Electrical
Conductivity and insulation.
Electrical Resistivity
Volume Resistivity
Surface Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
UV / Weathering Resistance
Same in both: Corrosion Resistance 85 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
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 | Carbon Fiber | Onyx |
|---|---|---|
| CNC machining | Yes | — |
| Sheet metal | Yes | — |
| 3D printing | — | Yes |
| Default condition | Epoxy Matrix | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Conductive Coating | — | Yes |
| Dyeing (Nylon) | — | Yes |
| EMI Shielding Coating | — | Yes |
| Primer Coating | — | Yes |
| Soft Touch Coating | — | Yes |
| Tinted Coating | — | Yes |
| UV Coating | — | Yes |
| Vacuum Metallization | — | Yes |
| Waterproof Coating | — | Yes |
They share 1 finish: Painting.
Carbon Fiber vs Onyx — frequently asked
Is Carbon Fiber stronger than Onyx?
Yes. Carbon Fiber has a typical tensile strength of 650 MPa (94.3 ksi) against 40 MPa (5.8 ksi) for Onyx — about 16 times as much.
Which is cheaper, Carbon Fiber or Onyx?
Carbon Fiber is the lower-cost material: it sits in the premium tier ($$$) while Onyx is high ($$$$). 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, Carbon Fiber or Onyx?
Onyx. Its machinability rates good (55/100) against fair (35/100) for Carbon Fiber.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Carbon Fiber and Onyx 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.