RPU GF30 vs RPU ISF
Polyurethane · RPU grade comparison
RPU GF30 and RPU ISF are two grades of the same polyurethane grade, RPU: GF30 (30% glass-fiber / milled-glass reinforced RIM-SRIM) versus ISF (integral-skin (self-skinning) rigid foam). The chemistry is identical, so every difference below comes from the condition. RPU GF30 is the stronger of the two: tensile strength 70 MPa (10.2 ksi) against 10 MPa (1.45 ksi) for RPU ISF, about 7.0 times as much. In exchange, RPU ISF is the more ductile: elongation 10% versus 2% for RPU GF30, and RPU GF30 is harder (80 Shore D vs 55 Shore D). RPU ISF is lighter (0.5 g/cm³ vs 1.38 g/cm³ for RPU GF30) and RPU GF30 is stiffer (6 GPa vs 0.5 GPa). On the shop floor, RPU ISF machines more easily (very good vs good).
RPU GF30Choose it when strength drives the design, or when the part sees heat.
RPU ISFChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
RPU GF30 vs RPU ISF: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polyurethane 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 polyurethane 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
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Same in both: Shear Modulus 0.87 GPa0.13 Msi · Bulk Modulus 3 GPa0.48 Msi · Poisson's Ratio 0.38 · Compressive Modulus 2.2 GPa0.32 Msi · Hardness, Rockwell M 75 HRM · Hardness, Rockwell R 110 HRR
Physical
Density and transition temperatures.
Density
Same in both: Glass Transition (Tg) 95°C203 °F · Water Absorption (24 h) 0.3% · Water Absorption (Saturation) 1.2%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Same in both: Specific Heat Capacity 1,600 J/kg·K0.38 BTU/lb·°F · Min Service Temperature -50°C-58 °F · Max Service Temperature (short-term) 130°C266 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 1×10¹¹ Ω·m3.94×10¹⁸ µΩ·in · Dielectric Strength 18 kV/mm457 V/mil · Dielectric Constant (1 MHz) 4 · Dissipation Factor (1 MHz) 0.04 · Volume Resistivity 1×10¹³ Ω·cm · Surface Resistivity 1×10¹³ Ω · Comparative Tracking Index (CTI) 600 V
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 70 / 100 · UV / Weathering Resistance 25 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Mold Shrinkage
Same in both: Polishability 60 / 100 · Processing Melt Temperature (typ.) 35°C95 °F · Mold Temperature (typ.) 55°C131 °F
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 103 MJ/kg44,282 BTU/lb · Embodied Carbon (primary production) 4.6 kg CO₂/kg · Embodied Water 230 L/kg27.6 gal/lb · Typical Recycled Content 3%
Strength versus weight
Yield strength against density for every polyurethane grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
RPU GF30 vs RPU ISF — frequently asked
Is RPU GF30 stronger than RPU ISF?
Yes. RPU GF30 has a typical tensile strength of 70 MPa (10.2 ksi) against 10 MPa (1.45 ksi) for RPU ISF — about 7.0 times as much.
Which grade does FabDigit quote by default, GF30 or ISF?
Cast is the default RPU condition in the FabDigit quote flow (neither GF30 nor ISF). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, RPU GF30 or RPU ISF?
RPU ISF. Its machinability rates very good (75/100) against good (55/100) for RPU GF30; for welding the order is RPU GF30 first (not recommended, 5/100) then RPU ISF (not recommended, 0/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in RPU GF30 and RPU ISF 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.