HR Foam vs Semi-Rigid PU Foam
Polymer · grade comparison
HR Foam and Semi-Rigid PU Foam are both polymer grades. Semi-Rigid PU Foam is the stronger of the two: tensile strength 0.55 MPa (0.0798 ksi) against 0.13 MPa (0.0189 ksi) for HR Foam, about 4.2 times as much. In exchange, HR Foam is the more ductile: elongation 130% versus 70% for Semi-Rigid PU Foam. HR Foam is lighter (0.05 g/cm³ vs 0.1 g/cm³ for Semi-Rigid PU Foam) and Semi-Rigid PU Foam is stiffer (0.01 GPa vs 2×10⁻⁵ GPa). On the shop floor, HR Foam machines more easily (excellent vs good).
HR FoamChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
Semi-Rigid PU FoamChoose it when strength drives the design.
HR Foam vs Semi-Rigid PU Foam: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Compressive Modulus
Tear Strength
Compression Set (22 h, 70 °C)
Flexural Strength
Flexural Modulus
Shear Strength
Hardness, Shore A
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Thermal Expansion (CTE, 20–100 °C)
Same in both: Thermal Conductivity 0.04 W/m·K0.02 BTU/hr·ft·°F · Specific Heat Capacity 1,500 J/kg·K0.36 BTU/lb·°F · Max Service Temperature (short-term) 120°C248 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Volume Resistivity
Dielectric Constant (1 MHz)
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
Weldability
Formability (cold)
Mold Shrinkage
Mold Temperature (typ.)
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
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.
Manufacturing and finishing
| Capability | HR Foam | Semi-Rigid PU Foam |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
HR Foam vs Semi-Rigid PU Foam — frequently asked
Is Semi-Rigid PU Foam stronger than HR Foam?
Yes. Semi-Rigid PU Foam has a typical tensile strength of 0.55 MPa (0.0798 ksi) against 0.13 MPa (0.0189 ksi) for HR Foam — about 4.2 times as much.
Which is cheaper, HR Foam or Semi-Rigid PU Foam?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, HR Foam or Semi-Rigid PU Foam?
HR Foam. Its machinability rates excellent (85/100) against good (55/100) for Semi-Rigid PU Foam.
Ready to make it?
Upload a CAD file and FabDigit prices the part in HR Foam and Semi-Rigid PU Foam 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.