Which Modified PTFE Sheet Is Suitable for Low-Friction Applications?
2026-10-19
A bearing application requires a material with a friction coefficient below 0.15 and a wear rate low enough to survive 10 million sliding cycles. The engineer considers pure PTFE. It has the lowest friction coefficient of any solid material, around 0.04 to 0.10. But the wear rate of pure PTFE is unacceptably high, on the order of 10⁻⁷ mm³/Nm, which means the bearing would fail long before 10 million cycles. The engineer must select a Modified PTFE Sheets with a filler that reduces wear without sacrificing the low-friction characteristic. The choice of filler determines whether the application succeeds or fails. This guide explains the trade-offs between different filler systems for low-friction applications.
1. Why Is Pure PTFE Unsuitable for Low-Friction Applications Despite Its Low Friction Coefficient?
Pure PTFE has the lowest friction coefficient of any unfilled polymer, but its wear resistance is poor. Under sliding contact, the PTFE chains slide over one another and transfer to the counterface, forming a transfer film. This film provides low friction, but it also means that the PTFE is being consumed. The wear rate is high, and the material can cold-flow under load. The table below shows the tribological properties of pure PTFE compared to filled grades.
| Material | Friction coefficient | Wear rate (mm³/Nm) | Limiting PV (MPa·m/s) |
| Pure PTFE | 0.04 – 0.10 | ~10⁻⁷ | ~2.5 |
| Glass-filled PTFE (17%) | 0.18 – 0.22 | ~10⁻⁸ | Moderate |
| Carbon-graphite filled PTFE | 0.10 – 0.20 | ~10⁻⁹ to 10⁻⁸ | High |
| Carbon fiber reinforced PTFE | 0.08 – 0.15 | ~10⁻⁹ | 3.80 (with Ni@Gr) |
In our factory, we supply Modified PTFE Sheets with several filler systems. The selection depends on whether the priority is the lowest possible friction, the lowest possible wear, or a balance of both. Ningbo Taifno PTFE Plastic Products Co., Ltd. has been compounding filled PTFE for over 12 years.
2. Which Filler System Provides the Best Balance for Low-Friction, Low-Wear Applications?
The best balance for most low-friction applications is achieved with a carbon-graphite filler system. Carbon reduces creep, increases hardness, and elevates thermal conductivity. Graphite provides solid lubrication and lowers the coefficient of friction. The combination produces a material with a friction coefficient of 0.10 to 0.20 and a wear rate two to three orders of magnitude lower than pure PTFE. The table below compares the filler systems for low-friction applications.
| Filler system | Friction coefficient | Wear resistance | Thermal conductivity | Best for |
| Graphite only | Low (0.08 – 0.15) | Moderate | Moderate | Corrosive service, low abrasion to soft shafts |
| Carbon-graphite | Low (0.10 – 0.20) | Excellent | High | Non-lubricated bearings, general low-friction |
| Carbon fiber | Low (0.08 – 0.15) | Excellent | High | High PV applications, fuel oil lubrication |
| Bronze | Moderate (0.15 – 0.25) | Good at ambient | High | High-load bearings, poor at high temp |
| Glass fiber | Moderate (0.18 – 0.22) | Good | Low | Creep resistance, oxidizing environments |
Tribology engineer's note: For a low-friction application where wear life is also critical, carbon-graphite filled PTFE is the starting point. It provides a friction coefficient in the 0.10 to 0.20 range and a wear rate that is 100 to 1,000 times lower than pure PTFE. If the application involves high PV (pressure × velocity) or fuel oil lubrication, carbon fiber reinforced grades with hybrid fillers can achieve friction coefficients as low as 0.02 to 0.03 and PV values up to 3.80 MPa·m/s [citation:3].
3. How Does the Operating Environment Change the Filler Selection?
The operating environment determines which filler system is suitable. In dry sliding against steel, glass fiber can abrade the counterface and increase wear. Carbon fiber and graphite are gentler on the counterface. In high-purity hydrogen gas, glass fiber causes severe abrasion on cast iron, while carbon fiber provides excellent low friction and low wear. In high-temperature applications above 100°C, bronze-filled PTFE has the poorest wear resistance, while carbon-graphite grades maintain moderate performance. The table below shows the environmental considerations.
| Environment | Preferred filler | Avoid | Reason |
| Dry sliding against steel | Carbon-graphite, carbon fiber | Glass fiber | Glass abrades the counterface |
| Hydrogen gas | Carbon fiber | Glass fiber | Glass causes severe abrasion in hydrogen |
| High temperature (>100°C) | Carbon-graphite | Bronze | Bronze has poorest high-temp wear |
| Corrosive chemicals | Graphite, carbon | Bronze, glass | Bronze corrodes; glass reacts with HF/base |
| High PV / high load | Carbon fiber, bronze | Graphite only | Carbon fiber and bronze provide load support |
In our factory, we provide application-specific Modified PTFE Sheets. For hydrogen service, we recommend carbon fiber filled grades. For chemical service, graphite filled grades. For high-temperature bearing applications, carbon-graphite. Taifno can supply test data for each grade to support the selection.
4. What Are the Trade-Offs Between Friction and Wear for Different Filler Loadings?
The filler loading affects both friction and wear. At low loading (below 5% by volume), the effect on properties is insignificant. At optimal loading (15 to 30% by volume), the wear resistance is maximized. At higher loading, the friction coefficient may increase, and the material may become brittle. The table below shows the effect of filler loading for carbon-graphite filled PTFE.
| Filler loading (vol%) | Friction coefficient | Wear rate (relative to pure PTFE) | Compressive strength |
| 0 (pure PTFE) | 0.04 – 0.10 | 1.0 (baseline) | Low |
| 10 – 15 | 0.08 – 0.12 | 0.01 – 0.05 | Moderate |
| 20 – 30 | 0.10 – 0.18 | 0.001 – 0.01 | High |
| 35 – 40 | 0.15 – 0.25 | 0.001 – 0.005 | Very high (but brittle) |
Selection rule of thumb: For low-friction applications, start with a 15 to 20% carbon-graphite filled PTFE sheet. This provides a friction coefficient around 0.10 to 0.15 and a wear rate that is 100 to 1,000 times lower than pure PTFE. If the application requires higher load capacity or higher PV, increase the loading to 25 to 30% or switch to a carbon fiber reinforced grade. If the application requires the absolute lowest friction coefficient and wear is not the primary concern, a graphite-only grade may be considered. Ningbo Taifno PTFE Plastic Products Co., Ltd. provides samples of each grade for evaluation.
Frequently Asked Questions About Modified PTFE Sheets for Low-Friction Applications
Summary for Tribology Engineers and Designers
The selection of a Modified PTFE Sheets for low-friction applications is a balance between friction coefficient and wear resistance. Pure PTFE has the lowest friction but unacceptably high wear. Carbon-graphite filled grades provide the best balance for most applications, with friction coefficients in the 0.10 to 0.20 range and wear rates 100 to 1,000 times lower than pure PTFE. Carbon fiber reinforced grades are suitable for high PV and fuel oil lubrication. Graphite-only grades are suitable for corrosive environments where low abrasion to the counterface is important. The operating environment, filler loading, and counterface finish all affect performance. Ningbo Taifno PTFE Plastic Products Co., Ltd. has been compounding filled PTFE for over 12 years and provides application-specific grades with full test data.
Ningbo Taifno PTFE Plastic Products Co., Ltd. manufactures Modified PTFE Sheets with graphite, carbon-graphite, carbon fiber, bronze, and glass fillers. We provide friction and wear test data, PV limits, and application recommendations for all of our products.
