PTMT GF20 vs PTMT HR
Polymer · PTMT grade comparison
PTMT GF20 and PTMT HR are two grades of the same polymer grade, PTMT: GF20 (20 % glass-fiber reinforced) versus HR (hot rolled). The chemistry is identical, so every difference below comes from the condition. PTMT HR is the stronger of the two: tensile strength 130 MPa (18.9 ksi) against 110 MPa (16 ksi) for PTMT GF20, about 18% more. In exchange, PTMT GF20 is the more ductile: elongation 3.5% versus 2.5% for PTMT HR. PTMT HR is lighter (1.31 g/cm³ vs 1.45 g/cm³ for PTMT GF20) and PTMT HR is stiffer (9.5 GPa vs 6.5 GPa). On the shop floor, PTMT GF20 welds better (very good vs fair).
PTMT GF20Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
PTMT HRChoose it when strength drives the design, or when weight is the constraint.
PTMT GF20 vs PTMT HR: 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
Compressive Strength
Flexural Strength
Flexural Modulus
Shear Strength
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Hardness, Rockwell R
Same in both: Shear Modulus 0.95 GPa0.14 Msi · Bulk Modulus 4 GPa0.58 Msi · Poisson's Ratio 0.4 · Yield Strength (0.2% offset) 55 MPa8 ksi · Compressive Modulus 2.4 GPa0.35 Msi
Physical
Density and transition temperatures.
Density
Same in both: Melting Temperature (Tm) 225°C437 °F · Glass Transition (Tg) 50°C122 °F · Water Absorption (24 h) 0.08% · Water Absorption (Saturation) 0.45% · Refractive Index 1.58
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Heat Deflection Temp. @ 0.45 MPa
Vicat Softening Point (B50)
Limiting Oxygen Index
Same in both: Specific Heat Capacity 1,500 J/kg·K0.36 BTU/lb·°F · Min Service Temperature -40°C-40 °F · Heat Deflection Temp. @ 1.8 MPa 205°C401 °F · Max Service Temperature (short-term) 160°C320 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Dielectric Strength 22 kV/mm559 V/mil · Dielectric Constant (1 MHz) 3.1 · Dissipation Factor (1 MHz) 0.018 · 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).
Corrosion Resistance
Same in both: UV / Weathering Resistance 35 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Mold Shrinkage
Same in both: Polishability 45 / 100 · Melt Flow Rate 25 g/10 min · Processing Melt Temperature (typ.) 255°C491 °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) 4.4 kg CO₂/kg · Embodied Water 250 L/kg30 gal/lb · Typical Recycled Content 5%
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.
PTMT GF20 vs PTMT HR — frequently asked
Is PTMT HR stronger than PTMT GF20?
Yes. PTMT HR has a typical tensile strength of 130 MPa (18.9 ksi) against 110 MPa (16 ksi) for PTMT GF20 — about 18% more.
Which grade does FabDigit quote by default, GF20 or HR?
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, PTMT GF20 or PTMT HR?
PTMT GF20, by a small margin. Both rate good for machinability — 68/100 against 62/100 for PTMT HR; for welding the order is PTMT GF20 first (very good, 70/100) then PTMT HR (fair, 50/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in PTMT GF20 and PTMT HR 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.