FR-2 vs FR-3
Composite · grade comparison
FR-2 and FR-3 are both composite grades. FR-3 is lighter (1.45 g/cm³ vs 1.55 g/cm³ for FR-2) and FR-3 is stiffer (9 GPa vs 7.5 GPa). On the shop floor, FR-2 sits in a lower cost tier (standard, $$) than FR-3 (premium, $$$).
FR-2Choose it when cost is the deciding factor.
FR-3Choose it when weight is the constraint.
FR-2 vs FR-3: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Same in both: Compressive Strength 250 MPa36.3 ksi · Hardness, Rockwell M 105 HRM
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (Saturation)
Same in both: Water Absorption (24 h) 0.55%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Min Service Temperature
Heat Deflection Temp. @ 1.8 MPa
Max Service Temperature (short-term)
Same in both: Specific Heat Capacity 1,300 J/kg·K0.31 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 20 µm/m·K11.1 µin/in·°F · Max Service Temperature (continuous) 105°C221 °F · Limiting Oxygen Index 30%
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
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)
Embodied Water
Typical Recycled Content
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 | FR-2 | FR-3 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
FR-2 vs FR-3 — frequently asked
What is the difference between FR-2 and FR-3?
FR-2 and FR-3 are both composite grades. FR-3 is lighter (1.45 g/cm³ vs 1.55 g/cm³ for FR-2) and FR-3 is stiffer (9 GPa vs 7.5 GPa). On the shop floor, FR-2 sits in a lower cost tier (standard, $$) than FR-3 (premium, $$$).
Which is cheaper, FR-2 or FR-3?
FR-2 is the lower-cost material: it sits in the standard tier ($$) while FR-3 is premium ($$$). 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, FR-2 or FR-3?
FR-3, by a small margin. Both rate very good for machinability — 80/100 against 75/100 for FR-2.
Ready to make it?
Upload a CAD file and FabDigit prices the part in FR-2 and FR-3 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.