PI 40% Graphite vs PI CF30
Polymer · PI grade comparison
PI 40% Graphite and PI CF30 are two grades of the same polymer grade, PI: 40% Graphite (40% Graphite filled) versus CF30 (30% carbon-fiber reinforced polyimide). The chemistry is identical, so every difference below comes from the condition. PI CF30 is the stronger of the two: tensile strength 100 MPa (14.5 ksi) against 52 MPa (7.54 ksi) for PI 40% Graphite, about 92% more. In exchange, PI 40% Graphite is the more ductile: elongation 3% versus 2% for PI CF30. PI CF30 is lighter (1.45 g/cm³ vs 1.65 g/cm³ for PI 40% Graphite) and PI CF30 is stiffer (12 GPa vs 6.2 GPa). On the shop floor, PI 40% Graphite machines more easily (45 vs 35 out of 100).
PI 40% GraphiteChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
PI CF30Choose it when strength drives the design, or when weight is the constraint.
PI 40% Graphite vs PI CF30: 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
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Flexural Strength
Flexural Modulus
Izod Impact, Notched
Hardness, Rockwell M
Same in both: Shear Modulus 1.1 GPa0.16 Msi · Bulk Modulus 6 GPa0.8 Msi · Poisson's Ratio 0.41 · Compressive Modulus 2.9 GPa0.42 Msi · Shear Strength 80 MPa11.6 ksi · Fracture Toughness (K_IC) 2 MPa·√m1.8 ksi·√in · Hardness, Shore D 88 Shore D
Physical
Density and transition temperatures.
Density
Same in both: Glass Transition (Tg) 385°C725 °F · Water Absorption (24 h) 0.3% · Water Absorption (Saturation) 1.2% · Refractive Index 1.7
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Same in both: Specific Heat Capacity 1,130 J/kg·K0.27 BTU/lb·°F · Max Service Temperature (continuous) 300°C572 °F · Min Service Temperature -240°C-400 °F · Heat Deflection Temp. @ 0.45 MPa 400°C752 °F · Heat Deflection Temp. @ 1.8 MPa 360°C680 °F · Limiting Oxygen Index 45% · Max Service Temperature (short-term) 480°C896 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Strength 22 kV/mm559 V/mil · Dielectric Constant (1 MHz) 3.5 · Dissipation Factor (1 MHz) 0.0034 · Volume Resistivity 1×10¹⁶ Ω·cm · Surface Resistivity 1×10¹⁵ Ω
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 85 / 100 · UV / Weathering Resistance 60 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Same in both: Weldability 5 / 100 · Formability (cold) 15 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 290 MJ/kg124,678 BTU/lb · Embodied Carbon (primary production) 13 kg CO₂/kg · Embodied Water 600 L/kg71.9 gal/lb · Typical Recycled Content 0%
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.
PI 40% Graphite vs PI CF30 — frequently asked
Is PI CF30 stronger than PI 40% Graphite?
Yes. PI CF30 has a typical tensile strength of 100 MPa (14.5 ksi) against 52 MPa (7.54 ksi) for PI 40% Graphite — about 92% more.
Which grade does FabDigit quote by default, 40% Graphite or CF30?
Specify the condition in the material field or the drawing note; FabDigit prices the quote for the state you call out.
Which is easier to machine, PI 40% Graphite or PI CF30?
PI 40% Graphite, by a small margin. Both rate fair for machinability — 45/100 against 35/100 for PI CF30.
Ready to make it?
Upload a CAD file and FabDigit prices the part in PI 40% Graphite and PI CF30 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.