SMA GF20 vs SMA GF40
Polymer · SMA grade comparison
SMA GF20 and SMA GF40 are two grades of the same polymer grade, SMA: GF20 (20% glass-fiber reinforced SMA) versus GF40 (40% glass-fiber reinforced SMA). The chemistry is identical, so every difference below comes from the condition. SMA GF40 is the stronger of the two: tensile strength 125 MPa (18.1 ksi) against 90 MPa (13.1 ksi) for SMA GF20, about 39% more. In exchange, SMA GF20 is the more ductile: elongation 1.8% versus 1.3% for SMA GF40. SMA GF20 is lighter (1.22 g/cm³ vs 1.38 g/cm³ for SMA GF40) and SMA GF40 is stiffer (11.5 GPa vs 6.5 GPa). On the shop floor, SMA GF20 machines more easily (fair vs poor).
SMA GF20Choose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
SMA GF40Choose it when strength drives the design.
SMA GF20 vs SMA GF40: 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
Tensile Strength (Ultimate)
Elongation at Break
Flexural Strength
Flexural Modulus
Izod Impact, Notched
Same in both: Shear Modulus 1.2 GPa0.17 Msi · Bulk Modulus 4 GPa0.54 Msi · Poisson's Ratio 0.35 · Yield Strength (0.2% offset) 50 MPa7.3 ksi · Compressive Strength 100 MPa14.5 ksi · Compressive Modulus 3.2 GPa0.46 Msi · Shear Strength 40 MPa5.8 ksi · Fracture Toughness (K_IC) 1.6 MPa·√m1.5 ksi·√in · Hardness, Shore D 85 Shore D · Hardness, Rockwell M 80 HRM · Hardness, Rockwell R 115 HRR
Physical
Density and transition temperatures.
Density
Same in both: Glass Transition (Tg) 140°C284 °F · Water Absorption (24 h) 0.2% · Water Absorption (Saturation) 0.7% · Refractive Index 1.57 · Light Transmission 85%
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. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Same in both: Thermal Conductivity 0.17 W/m·K0.1 BTU/hr·ft·°F · Specific Heat Capacity 1,400 J/kg·K0.33 BTU/lb·°F · Min Service Temperature -30°C-22 °F · Vicat Softening Point (B50) 135°C275 °F · Limiting Oxygen Index 18% · Max Service Temperature (short-term) 130°C266 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Strength 20 kV/mm508 V/mil · Dielectric Constant (1 MHz) 2.9 · Dissipation Factor (1 MHz) 0.008 · Volume Resistivity 1×10¹⁶ Ω·cm · Surface Resistivity 1×10¹⁵ Ω · Comparative Tracking Index (CTI) 600 V
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 60 / 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 55 / 100 · Formability (cold) 25 / 100 · Polishability 60 / 100 · Melt Flow Rate 4 g/10 min · Processing Melt Temperature (typ.) 245°C473 °F · Mold Temperature (typ.) 70°C158 °F
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 95 MJ/kg40,843 BTU/lb · Embodied Carbon (primary production) 3.6 kg CO₂/kg · Embodied Water 160 L/kg19.2 gal/lb · Typical Recycled Content 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.
SMA GF20 vs SMA GF40 — frequently asked
Is SMA GF40 stronger than SMA GF20?
Yes. SMA GF40 has a typical tensile strength of 125 MPa (18.1 ksi) against 90 MPa (13.1 ksi) for SMA GF20 — about 39% more.
Which grade does FabDigit quote by default, GF20 or GF40?
UF is the default SMA condition in the FabDigit quote flow (neither GF20 nor GF40). 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, SMA GF20 or SMA GF40?
SMA GF20. Its machinability rates fair (40/100) against poor (30/100) for SMA GF40.
Ready to make it?
Upload a CAD file and FabDigit prices the part in SMA GF20 and SMA GF40 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.