HDPE GF20 vs HDPE GF30
Polymer · HDPE grade comparison
HDPE GF20 and HDPE GF30 are two grades of the same polymer grade, HDPE: GF20 (20% Glass Fiber) versus GF30 (30% glass fiber reinforced HDPE). The chemistry is identical, so every difference below comes from the condition. HDPE GF20 is the stronger of the two: yield strength 50 MPa (7.25 ksi) against 26 MPa (3.77 ksi) for HDPE GF30, about 92% more. HDPE GF20 is lighter (1.08 g/cm³ vs 1.18 g/cm³ for HDPE GF30) and HDPE GF30 is stiffer (5.5 GPa vs 4.2 GPa). On the shop floor, HDPE GF30 forms better (very good vs poor).
HDPE GF20Choose it when strength drives the design, or when weight is the constraint.
HDPE GF20 vs HDPE GF30: 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
Yield Strength (0.2% offset)
Compressive 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 · Tensile Strength (Ultimate) 55 MPa8 ksi · Elongation at Break 3% · Compressive Modulus 0.9 GPa0.13 Msi · Flexural Strength 70 MPa10.2 ksi · 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
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Surface Resistivity 1×10¹⁵ Ω · 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)
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 2 kg CO₂/kg · 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 GF20 vs HDPE GF30 — frequently asked
Is HDPE GF20 stronger than HDPE GF30?
Yes. HDPE GF20 has a typical yield strength of 50 MPa (7.25 ksi) against 26 MPa (3.77 ksi) for HDPE GF30 — about 92% more. Tensile strength is 55 MPa (7.98 ksi) vs 55 MPa (7.98 ksi).
Which grade does FabDigit quote by default, GF20 or GF30?
Specify the condition in the material field or the drawing note; FabDigit prices the quote for the state you call out.
Which is easier to machine, HDPE GF20 or HDPE GF30?
HDPE GF20. Its machinability rates good (55/100) against fair (50/100) for HDPE GF30; for welding the order is HDPE GF30 first (fair, 45/100) then HDPE GF20 (fair, 40/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in HDPE GF20 and HDPE GF30 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.