SPF vs Viscoelastic PU Foam
Polymer · grade comparison
SPF and Viscoelastic PU Foam are both polymer grades. SPF is the stronger of the two: tensile strength 0.3 MPa (0.0435 ksi) against 0.1 MPa (0.0145 ksi) for Viscoelastic PU Foam, about 200% more. In exchange, Viscoelastic PU Foam is the more ductile: elongation 150% versus 8% for SPF. SPF is lighter (0.03 g/cm³ vs 0.05 g/cm³ for Viscoelastic PU Foam) and SPF is stiffer (0.01 GPa vs 2.5×10⁻⁴ GPa). On the shop floor, SPF machines more easily (excellent vs good), Viscoelastic PU Foam welds better (poor vs not recommended), and SPF sits in a lower cost tier (standard, $$) than Viscoelastic PU Foam (premium, $$$).
SPFChoose it when strength drives the design, or when weight is the constraint.
Viscoelastic PU FoamChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
SPF vs Viscoelastic 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
Flexural Strength
Flexural Modulus
Shear Strength
Tear Strength
Compression Set (22 h, 70 °C)
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
Thermal Expansion (CTE, 20–100 °C)
Min Service Temperature
Limiting Oxygen Index
Same in both: Max Service Temperature (continuous) 90°C194 °F · Max Service Temperature (short-term) 120°C248 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Volume Resistivity
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.
Machinability
Weldability
Formability (cold)
Polishability
Processing Melt Temperature (typ.)
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)
Same in both: Thermal Diffusivity 0.5 mm²/s
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 | SPF | Viscoelastic PU Foam |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
SPF vs Viscoelastic PU Foam — frequently asked
Is SPF stronger than Viscoelastic PU Foam?
Yes. SPF has a typical tensile strength of 0.3 MPa (0.0435 ksi) against 0.1 MPa (0.0145 ksi) for Viscoelastic PU Foam — about 200% more.
Which is cheaper, SPF or Viscoelastic PU Foam?
SPF is the lower-cost material: it sits in the standard tier ($$) while Viscoelastic PU Foam is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, SPF or Viscoelastic PU Foam?
SPF. Its machinability rates excellent (85/100) against good (60/100) for Viscoelastic PU Foam; for welding the order is Viscoelastic PU Foam first (poor, 30/100) then SPF (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SPF and Viscoelastic 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.