HDPE GF30 vs HDPE GF40
Polymer · HDPE grade comparison
HDPE GF30 and HDPE GF40 are two grades of the same polymer grade, HDPE: GF30 (30% glass fiber reinforced HDPE) versus GF40 (40% Glass Fiber). The chemistry is identical, so every difference below comes from the condition. HDPE GF40 is the stronger of the two: yield strength 78 MPa (11.3 ksi) against 26 MPa (3.77 ksi) for HDPE GF30, about 3.0 times as much; tensile strength follows at 80 MPa (11.6 ksi) vs 55 MPa (7.98 ksi). In exchange, HDPE GF30 is the more ductile: elongation 3% versus 2% for HDPE GF40. HDPE GF30 is lighter (1.18 g/cm³ vs 1.26 g/cm³ for HDPE GF40) and HDPE GF40 is stiffer (7.8 GPa vs 5.5 GPa). On the shop floor, HDPE GF30 welds better (fair vs poor).
HDPE GF30Choose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
HDPE GF40Choose it when strength drives the design, or when the part sees heat.
HDPE GF30 vs HDPE 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
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Flexural Strength
Flexural Modulus
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Same in both: Shear Modulus 0.4 GPa0.06 Msi · Bulk Modulus 3 GPa0.44 Msi · Compressive Modulus 0.9 GPa0.13 Msi · Shear Strength 20 MPa2.9 ksi · Fracture Toughness (K_IC) 2 MPa·√m1.8 ksi·√in
Physical
Density and transition temperatures.
Density
Water Absorption (24 h)
Water Absorption (Saturation)
Same in both: Melting Temperature (Tm) 132°C270 °F · Glass Transition (Tg) -110°C-166 °F · Refractive Index 1.54
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Max Service Temperature (short-term)
Same in both: Vicat Softening Point (B50) 76°C169 °F
Electrical
Conductivity and insulation.
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Surface Resistivity
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Comparative Tracking Index (CTI) 600 V
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 Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Same in both: Polishability 30 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 90 L/kg10.8 gal/lb
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.
HDPE GF30 vs HDPE GF40 — frequently asked
Is HDPE GF40 stronger than HDPE GF30?
Yes. HDPE GF40 has a typical yield strength of 78 MPa (11.3 ksi) against 26 MPa (3.77 ksi) for HDPE GF30 — about 3.0 times as much. Tensile strength is 80 MPa (11.6 ksi) vs 55 MPa (7.98 ksi).
Which grade does FabDigit quote by default, GF30 or GF40?
Specify the condition in the material field or the drawing note; FabDigit prices the quote for the state you call out.
Which welds better, HDPE GF30 or HDPE GF40?
HDPE GF30. Its weldability rates fair (45/100) against poor (30/100) for HDPE GF40.
Ready to make it?
Upload a CAD file and FabDigit prices the part in HDPE GF30 and HDPE 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.