PTFE-GF25 GF25
Reinforced grade · default condition
GF25 = 25% glass-fiber filled PTFE, compression moulded
Default general-purpose grade for valve seats, seals, wear rings and gaskets needing low creep and low friction.
Values for the GF25 condition
Other PTFE-GF25 grades and fills
PTFE-GF25 is listed in 6 conditions; see the grade overview at PTFE-GF25.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
GF25DefaultThis page 25% glass-fiber filled PTFE, compression moulded | Default general-purpose grade for valve seats, seals, wear rings and gaskets needing low creep and low friction. | 12 | 16 | 250 | 62 Shore D |
glass fiber plus molybdenum disulphide (bearing grade) | Pick when dry-running wear life and lower running friction matter more than colour or electrical properties (dark grey compound). | 12 | 14 | 200 | 63 Shore D |
GF25 milled-fiber | Choose for smoother sealing faces and more isotropic shrinkage in thin parts; slightly lower creep resistance than chopped fiber. | 12 | 15 | 260 | 61 Shore D |
GF25 ram-extruded rod / tube stock | Use for long machining stock in small diameters; properties slightly anisotropic and typically a few percent below moulded stock. | 12 | 15 | 230 | 62 Shore D |
GF25 FDA / food-contact compliant compound | Specify when food, pharma or potable-water contact compliance (FDA 21 CFR 177.1550 / EU 10/2011) is required — same mechanicals, certified virgin resin and filler. | 12 | 16 | 250 | 62 Shore D |
GF25 chopped-fiber | Choose for maximum creep/compression resistance in thick valve seats and heavily loaded wear parts. | 13 | 17 | 220 | 63 Shore D |
What is PTFE-GF25 GF25?
PTFE-GF25 GF25 is PTFE-GF25 in the GF25 grade — default general-purpose grade for valve seats, seals, wear rings and gaskets needing low creep and low friction. PTFE-GF25 GF25 has a yield strength of 12 MPa (1.74 ksi) and a tensile strength of 16 MPa (2.32 ksi) — weaker than 88% of polymer grades. Elongation at break is 250% and the elastic modulus is 1.2 GPa (0.174 Msi). PTFE-GF25 GF25 has a density of 2.23 g/cm³ (0.0806 lb/in³), heavier than 100% of polymer grades.
Advantages
- High service temperature — 260°C (500 °F), better than 97% of polymer grades
- Good UV / weathering resistance — 95/100, better than 95% of polymer grades
- Conducts heat well — 0.4 W/m·K (0.231 BTU/hr·ft·°F), better than 93% of polymer grades
- Low moisture uptake — 0.03%, better than 88% of polymer grades
- Ductile — tolerates forming and impact — 250%, better than 79% of polymer grades
Limitations
- Heavy — 2.23 g/cm³ (0.0806 lb/in³), worse than 100% of polymer grades
- Hard to polish — 20/100, worse than 95% of polymer grades
- High mold shrinkage — 2.5%, worse than 93% of polymer grades
- Difficult to weld — 5/100, worse than 89% of polymer grades
- Low strength — 12 MPa (1.74 ksi), worse than 88% of polymer grades
PTFE-GF25 GF25 properties
Typical room-temperature values for PTFE-GF25 GF25; 23 are specific to this condition. Other listed values are PTFE-GF25 reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
PTFE-GF25 GF25 has a density of 2.23 g/cm³ (0.0806 lb/in³), heavier than 100% of polymer grades.
Mechanical14
PTFE-GF25 GF25 has a yield strength of 12 MPa (1.74 ksi) and a tensile strength of 16 MPa (2.32 ksi) — weaker than 88% of polymer grades. Elongation at break is 250% and the elastic modulus is 1.2 GPa (0.174 Msi).
Thermal10
PTFE-GF25 GF25 is rated for continuous service to 260°C (500 °F). It conducts heat at 0.4 W/m·K (0.231 BTU/hr·ft·°F), better than 93% of polymer grades. Thermal expansion is 75 µm/m·K (41.7 µin/in·°F).
Electrical7
PTFE-GF25 GF25 is an electrical insulator with a dielectric strength of 14 kV/mm (355.6 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 74% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PTFE-GF25 GF25 takes about 170 MJ of energy and emits 9 kg of CO₂ — more than 86% of polymer grades. Typical recycled content is 0%.
Manufacturability6
PTFE-GF25 GF25's machinability is very good (70/100, better than 74% of polymer grades); weldability not recommended (5/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PTFE-GF25 GF25
Is PTFE-GF25 easy to machine?
Machines easily with sharp positive-rake carbide (PCD for long runs) at high speed and light feed; glass is abrasive and the part is soft, so support thin walls, avoid heat build-up, and expect springback and burr rather than chips.
Can PTFE-GF25 be welded?
Not melt-weldable; join by mechanical clamping, adhesive bonding after sodium-etch/plasma surface activation, or by fusing to unfilled PTFE film during sintering.
Can PTFE-GF25 be formed, bent or molded?
Processed as a powder: cold compaction of a preform then free sintering at 370–380 °C with slow controlled cooling; not injection-mouldable and shrinkage on sinter is 2–5 %, so allow machining stock.
What surface finishes work on PTFE-GF25?
Cannot be painted or plated as-is; use sodium-naphthalene etch or plasma treatment for bondable surfaces, and note that machined faces stay matte white/grey and cannot be polished to gloss.
PTFE-GF25 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| glass fiberE-glass, milled or chopped strand; wt % | 23 – 27 | 25 |
| polytetrafluoroethylene (PTFE)TFE homopolymer matrix, granular moulding resin | ≥ 73 (balance) | — |
PTFE-GF25 GF25 — frequently asked
What is PTFE-GF25 GF25 used for?
PTFE-GF25 GF25 is typically used for rotary shaft seals, piston rings, bearing pads and wear rings and valve seats. In short: low-creep filled PTFE; cheapest PTFE wear compound; not for HF or strong alkali.
What is the yield strength of PTFE-GF25 GF25?
PTFE-GF25 GF25 has a typical yield strength of 12 MPa (1.74 ksi) and a tensile strength of 16 MPa (2.32 ksi) — weaker than 88% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is PTFE-GF25 GF25 easy to machine?
Yes — machinability is rated very good (70/100, better than 74% of polymer grades). Machines easily with sharp positive-rake carbide (PCD for long runs) at high speed and light feed; glass is abrasive and the part is soft, so support thin walls, avoid heat build-up, and expect springback and burr rather than chips.
Can PTFE-GF25 GF25 be welded?
Not readily — weldability is rated not recommended (5/100). Not melt-weldable; join by mechanical clamping, adhesive bonding after sodium-etch/plasma surface activation, or by fusing to unfilled PTFE film during sintering.
What surface finishes work on PTFE-GF25 GF25?
Cannot be painted or plated as-is; use sodium-naphthalene etch or plasma treatment for bondable surfaces, and note that machined faces stay matte white/grey and cannot be polished to gloss.
Can PTFE-GF25 GF25 be formed, bent or molded?
Processed as a powder: cold compaction of a preform then free sintering at 370–380 °C with slow controlled cooling; not injection-mouldable and shrinkage on sinter is 2–5 %, so allow machining stock.
What is the maximum service temperature of PTFE-GF25 GF25?
PTFE-GF25 GF25 is rated for continuous use to about 260°C (500 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D4745 — Filled and Unfilled PTFE Molding and Extrusion Materials — ASTM International (2021)
- ASTM D1710 — PTFE Rod, Heavy-Walled Tubing and Basic Shapes — ASTM International (2019)
- GB/T 5132 / GB/T 20020 — SAC (2019)
- Engineered Materials Handbook, Vol. 2: Engineering Plastics — ASM International (1988)
- Filled PTFE compound datasheets (glass-fiber grades) — Ensinger / Enflo / Daikin / Chemours licensees (2023)
- CAMPUS / UL Prospector fluoropolymer compound data — CWFG / UL (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.