EPS vs SAN
Polymer · grade comparison
EPS and SAN are both polymer grades. SAN is the stronger of the two: yield strength 70 MPa (10.2 ksi) against 0.2 MPa (0.029 ksi) for EPS, about 350 times as much; tensile strength follows at 72 MPa (10.4 ksi) vs 0.25 MPa (0.0363 ksi). EPS is lighter (0.02 g/cm³ vs 1.07 g/cm³ for SAN) and SAN is stiffer (3.6 GPa vs 0.01 GPa). On the shop floor, EPS machines more easily (excellent vs good), SAN welds better (very good vs fair), and EPS forms better (very good vs fair).
EPSChoose it when weight is the constraint, or when the part is machined in volume.
SANChoose it when strength drives the design, or when it will be welded.
EPS vs SAN: 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)
Yield Strength (0.2% offset)
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Shear Modulus
Bulk Modulus
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Hardness, Rockwell R
Same in both: Elongation at Break 3%
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
Light Transmission
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Vicat Softening Point (B50)
Limiting Oxygen Index
Max Service Temperature (short-term)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Same in both: Specific Heat Capacity 1,350 J/kg·K0.32 BTU/lb·°F
Electrical
Conductivity and insulation.
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Dielectric Strength
Surface Resistivity
Comparative Tracking Index (CTI)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Volume Resistivity 1×10¹⁶ Ω·cm
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)
Mold Temperature (typ.)
Polishability
Melt Flow Rate
Processing Melt Temperature (typ.)
Same in both: Mold Shrinkage 0.5%
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)
Modulus of Resilience
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 0
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 | EPS | SAN |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
EPS vs SAN — frequently asked
Is SAN stronger than EPS?
Yes. SAN has a typical yield strength of 70 MPa (10.2 ksi) against 0.2 MPa (0.029 ksi) for EPS — about 350 times as much. Tensile strength is 72 MPa (10.4 ksi) vs 0.25 MPa (0.0363 ksi).
Which is cheaper, EPS or SAN?
EPS is the lower-cost material: it sits in the budget tier ($) while SAN is standard ($$). 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, EPS or SAN?
EPS. Its machinability rates excellent (90/100) against good (60/100) for SAN; for welding the order is SAN first (very good, 70/100) then EPS (fair, 45/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in EPS and SAN 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.