HR Foam vs SPF
Polymer · grade comparison
HR Foam and SPF are both polymer grades. SPF is the stronger of the two: tensile strength 0.3 MPa (0.0435 ksi) against 0.13 MPa (0.0189 ksi) for HR Foam, about 131% more. In exchange, HR Foam is the more ductile: elongation 130% versus 8% for SPF. SPF is lighter (0.03 g/cm³ vs 0.05 g/cm³ for HR Foam) and SPF is stiffer (0.01 GPa vs 2×10⁻⁵ GPa). On the shop floor, HR Foam welds better (fair vs not recommended).
HR FoamChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
SPFChoose it when strength drives the design, or when weight is the constraint.
HR Foam vs SPF: 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
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.
Thermal Conductivity
Specific Heat Capacity
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Thermal Expansion (CTE, 20–100 °C)
Same in both: 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
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Weldability
Formability (cold)
Polishability
Processing Melt Temperature (typ.)
Same in both: Machinability 85 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 5 kg CO₂/kg
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 | SPF |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
HR Foam vs SPF — frequently asked
Is SPF stronger than HR Foam?
Yes. SPF has a typical tensile strength of 0.3 MPa (0.0435 ksi) against 0.13 MPa (0.0189 ksi) for HR Foam — about 131% more.
Which is cheaper, HR Foam or SPF?
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 welds better, HR Foam or SPF?
HR Foam. Its weldability rates fair (40/100) against not recommended (5/100) for SPF.
Ready to make it?
Upload a CAD file and FabDigit prices the part in HR Foam and SPF 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.