RPU Cast vs RPU GF30
Polyurethane · RPU grade comparison
RPU Cast and RPU GF30 are two grades of the same polyurethane grade, RPU: Cast (as cast) versus GF30 (30% glass-fiber / milled-glass reinforced RIM-SRIM). 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 55 MPa (7.98 ksi) for RPU Cast, about 27% more. In exchange, RPU Cast is the more ductile: elongation 6% versus 2% for RPU GF30. RPU Cast is lighter (1.15 g/cm³ vs 1.38 g/cm³ for RPU GF30) and RPU GF30 is stiffer (6 GPa vs 2.4 GPa). On the shop floor, RPU Cast machines more easily (excellent vs good).
RPU CastChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
RPU GF30Choose it when strength drives the design, or when the part sees heat.
RPU Cast vs RPU GF30: 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
Izod Impact, Notched
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 · Shear Strength 40 MPa5.8 ksi · Fracture Toughness (K_IC) 1.3 MPa·√m1.2 ksi·√in · Hardness, Shore D 80 Shore D · 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 Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Heat Deflection Temp. @ 1.8 MPa
Same in both: Thermal Conductivity 0.21 W/m·K0.12 BTU/hr·ft·°F · Specific Heat Capacity 1,600 J/kg·K0.38 BTU/lb·°F · Min Service Temperature -50°C-58 °F · Heat Deflection Temp. @ 0.45 MPa 85°C185 °F · Limiting Oxygen Index 22% · 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
Mold Shrinkage
Same in both: Weldability 5 / 100 · Formability (cold) 5 / 100 · 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 Cast vs RPU GF30 — frequently asked
Is RPU GF30 stronger than RPU Cast?
Yes. RPU GF30 has a typical tensile strength of 70 MPa (10.2 ksi) against 55 MPa (7.98 ksi) for RPU Cast — about 27% more.
Which grade does FabDigit quote by default, Cast or GF30?
Cast is the default RPU condition in the FabDigit quote flow. 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 Cast or RPU GF30?
RPU Cast. Its machinability rates excellent (85/100) against good (55/100) for RPU GF30.
Ready to make it?
Upload a CAD file and FabDigit prices the part in RPU Cast and RPU GF30 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.