Views: 0 Author: Site Editor Publish Time: 2026-09-09 Origin: Site
Bearing-grade PEEK is generally the better starting point for continuous dry-sliding applications where low friction and wear resistance are the primary requirements. CF30 PEEK is often preferred when structural stiffness, dimensional stability, and load-bearing capability are more important. Neither grade is universally better for wear because tribological performance depends on PV, temperature, counter-face material, surface finish, lubrication, and the specific formulation.
The key engineering point is that CF30 PEEK and bearing-grade PEEK are optimized for different purposes. CF30 relies primarily on carbon-fiber reinforcement to improve stiffness, strength, dimensional stability, and wear behavior. Bearing-grade PEEK typically combines reinforcement with solid lubricants such as PTFE and graphite to reduce friction and improve dry-sliding performance.
For this reason, carbon-fiber reinforcement alone should not automatically be treated as a substitute for a dedicated bearing-grade formulation.
| Requirement | CF30 PEEK | Bearing-Grade PEEK |
|---|---|---|
| Structural stiffness | Excellent | Good |
| Load-bearing capability | Excellent | Good to excellent |
| Dimensional stability | Excellent | Good |
| Low friction | Moderate to good* | Excellent* |
| Dry-sliding wear | Good to excellent* | Excellent* |
| High-PV dry sliding | Application-dependent | Preferred starting point* |
| Continuous dry running | Application-dependent | Preferred starting point* |
| Main design priority | Stiffness + load | Friction + wear |
| Typical formulation approach | PEEK + carbon fiber | PEEK + reinforcement + solid lubricants |
*Performance depends on the specific formulation and test conditions. These rankings are engineering guidance rather than universal material limits.
Choose CF30 PEEK when the component is primarily structural and also experiences sliding or wear. Choose bearing-grade PEEK when friction, dry-running capability, and wear are the primary design requirements.
Not necessarily.
CF30 PEEK can provide good wear performance, particularly under low to moderate PV conditions, while offering substantially higher stiffness and strength than many bearing-grade formulations.
However, a dedicated bearing-grade formulation can provide lower friction and more stable tribological behavior under demanding dry-sliding conditions because it is specifically formulated with solid lubricants.
The distinction is therefore:
CF30 is primarily a structural reinforcement grade with useful tribological performance, while bearing-grade PEEK is primarily optimized for friction and wear.
This distinction is more useful for material selection than simply asking which grade has the "best wear resistance."
The following tribological comparison is based on published data for Victrex PEEK 450CA30, 450FC30, and WG101.
These Victrex grades are used here to illustrate the behavior of different PEEK formulations. The published Victrex data should not be interpreted as specification data for PRES CF30 or PRES Bearing Grade.
The published comparison uses:
ASTM G137 block-on-ring
Unlubricated sliding
High-speed / high-load conditions
Victrex grades 450CA30, 450FC30, and WG101
The limiting-PV data discussed below uses a modified ASTM D3702 thrust-washer geometry.
| Test condition | Victrex 450CA30 | Victrex 450FC30 |
|---|---|---|
| 1 m/s, 5 MPa (PV 5) | ~0.26 | ~0.42 |
| 2 m/s, 7.5 MPa (PV 15) | ~0.66 | ~0.34 |
| Change | +154% | −19% |
The important observation is not simply which material has the lower friction coefficient at one operating point.
It is the change in friction behavior as PV increases.
Under the published test conditions:
450CA30 starts with a lower friction coefficient at PV 5.
At PV 15, its friction coefficient increases substantially.
450FC30 starts higher but decreases under the higher-speed, higher-pressure condition.
This illustrates why a carbon-fiber-reinforced PEEK grade should not automatically be considered equivalent to a dedicated bearing-grade formulation.
A material that performs well at low PV may not remain the best choice as pressure and sliding speed increase.
For applications with increasing PV, the complete formulation and tribological system should be evaluated rather than selecting a grade based only on fiber reinforcement.
Under the published test conditions, 450FC30 shows approximately one-third the specific wear rate of 450CA30.
The CA30 wear rate remains relatively high and approximately flat across the two reported conditions, while the bearing-grade formulation shows substantially lower wear.
This supports a practical distinction:
CF30: useful when structural performance and moderate tribological duty must be combined.
Bearing grade: more appropriate when minimizing friction and wear is the primary objective.
The limiting PV, or Lpv, is the pressure × velocity condition at which excessive wear, interfacial melting, or severe scoring occurs under the specified test method.
Published values include:
| Grade category | Friction coefficient | Lpv |
|---|---|---|
| Carbon fiber, no wear additives — 450CA30, HT 22CA30 | ~0.25 | Below 7 MPa·m/s |
| Standard wear grades — 150FW30, 450FC30 | ~0.20 | 6–9 MPa·m/s |
| Premium wear grades — WG101, WG102 | 0.05–0.15 | 10–18 MPa·m/s |
These values are test results for the specified grades and test configuration, not universal continuous-service ratings.
One additional limitation reported in the published data is important: once the counter-face temperature reaches approximately 300 °C, the tested samples fail regardless of grade.
The difference is primarily related to formulation.
CF30 uses carbon fiber to improve:
stiffness
strength
dimensional stability
thermal stability
load-bearing capability
Carbon-fiber reinforcement can also contribute to tribological performance through transfer-film formation and improved heat dissipation.
However, carbon fiber alone does not provide the same lubricating effect as a formulation containing dedicated solid lubricants.
Bearing-grade PEEK formulations may combine reinforcement with solid lubricants such as:
PTFE
graphite
other formulation-specific tribological additives
These additives can reduce interfacial shear and help maintain a lubricating transfer film during sliding.
Therefore:
Carbon fiber primarily helps PEEK carry load and maintain stiffness, while solid lubricants are used to reduce friction and improve tribological behavior.
The exact formulation varies by manufacturer and grade, so performance should always be evaluated using grade-specific data.
CF30 PEEK is generally the better starting point when the component must combine structural performance with moderate sliding or wear requirements.
Consider CF30 when:
CF30 provides substantially higher stiffness than unfilled PEEK and can be advantageous when deformation must be minimized.
The PRES reference data cited in this article gives CF30 a tensile strength of approximately 250 MPa, compared with approximately 140 MPa for the referenced bearing-grade formulation.
The PRES CF30 reference data gives a coefficient of thermal expansion of approximately 15 ppm/K and an HDT of approximately 336 °C.
Under the published test conditions discussed here, CF30 can provide acceptable friction and wear performance at low to moderate PV.
For a structural component that also slides against another surface, CF30 may provide a better balance of stiffness, strength, dimensional stability, and wear performance than a softer tribological formulation.
Bearing-grade PEEK is generally the better starting point when the primary design requirements are:
low friction
dry-running capability
wear resistance
stable tribological behavior
higher PV operation
reduced frictional heat generation
Typical applications include:
bushings
bearings
wear rings
sliding guides
thrust washers
seals with sliding contact
other continuously sliding components
However, "bearing grade" is not a universal material specification. Different suppliers use different formulations, so the exact grade, filler system, counter-face, temperature, surface finish, and operating conditions must be considered.
A practical selection process is:
For a sliding interface:
PV = Pressure × Sliding Velocity
For a cylindrical sliding component:
P = Load / (d × L)
where:
P = contact pressure, MPa
d = diameter, mm
L = projected bearing length, mm
Sliding velocity can be estimated from:
V = πdn / 60000
where:
V = sliding velocity, m/s
d = diameter, mm
n = rotational speed, rpm
Higher temperature can reduce the allowable tribological duty of PEEK.
The temperature at the actual sliding interface can be more important than the bulk temperature of the component.
If the component is primarily structural:
Start with CF30.
If the component is primarily a sliding/wear component:
Start with a bearing-grade formulation.
Consider:
steel
stainless steel
hardened steel
aluminum
other polymers
surface roughness
surface treatment
Tribological performance is a property of the complete tribosystem, not the polymer alone.
Dry running, oil lubrication, grease lubrication, and water lubrication can produce very different friction and wear results.
Published dry-sliding data should therefore not be directly transferred to a lubricated application.
If the application operates near the material's limiting PV, or if temperature and counter-face conditions are unusual, application-specific testing is recommended.
The PV 5 and PV 15 test conditions discussed above are accelerated laboratory conditions. They are useful for comparing grades under controlled conditions, but they should not be treated as continuous service ratings.
A conservative screening approach can be obtained by applying a safety factor to the published limiting-PV values:
| Material category | Published Lpv | Illustrative continuous dry-PV screening range |
|---|---|---|
| CF30 / carbon-fiber PEEK | <7 MPa·m/s | ~0.2–0.35 MPa·m/s |
| Bearing-grade PEEK | 6–9 MPa·m/s | ~0.30–0.50 MPa·m/s |
These ranges are engineering screening values derived from the published Lpv data. They are not manufacturer-rated continuous PV limits.
The approximately 0.3 MPa·m/s value can therefore be used as an initial screening point in the context discussed here, but it should not be interpreted as a universal boundary between CF30 and bearing-grade PEEK.
Actual allowable PV depends on:
temperature
pressure
sliding velocity
counter-face material
surface roughness
lubrication
duty cycle
component geometry
specific PEEK formulation
Temperature should be considered separately from PV.
As interface temperature increases, PEEK mechanical and tribological performance can change significantly.
The original engineering screening approach used in this analysis applies approximate reductions to allowable PV as temperature increases:
| Temperature | Approximate PV factor |
|---|---|
| 100 °C | ×0.75 |
| 150 °C | ×0.50 |
| 200 °C | ×0.30 |
These factors are conservative engineering screening assumptions, not universal material specifications.
If the sliding interface approaches very high temperatures, application-specific testing becomes increasingly important.
Wear is a tribosystem property, not a material constant.
Friction and wear can change substantially with:
counter-face material
surface roughness
contact pressure
sliding velocity
temperature
lubrication
alignment
duty cycle
transfer-film formation
Therefore, published wear data should be used for material screening and grade comparison, not treated as a universal design allowable.
The most reliable conclusion from the published comparison is not that one grade always wins.
It is this:
CF30 and bearing-grade PEEK should be selected for different engineering priorities. CF30 is generally favored when stiffness and load-bearing capability are critical, while bearing-grade PEEK is generally favored when low friction and dry-sliding wear performance are the primary requirements.
No. Published Victrex data should not be treated as specification data for PRES PEEK grades.
The Victrex grades discussed in this article — 450CA30, 450FC30 and WG101 — are specific commercial formulations.
PRES CF30 and PRES Bearing Grade are discussed here as formulation categories with comparable reinforcement concepts, not as identical materials.
Published Victrex data can therefore be used to:
understand general PEEK tribological mechanisms
compare formulation concepts
establish engineering hypotheses
guide preliminary material selection
For final material selection, use the grade-specific PRES datasheet and, where necessary, application-specific testing.
Generally, bearing-grade PEEK is the better starting point when low friction and continuous dry-sliding wear are the primary requirements. CF30 may be preferable when structural stiffness, dimensional stability, and load-bearing capability are more important.
CF30 PEEK can be used in some sliding and wear applications, but carbon-fiber reinforcement alone does not make a PEEK grade equivalent to a dedicated bearing formulation. Bearing-grade PEEK typically includes additional tribological additives designed to reduce friction and wear.
Under the published Victrex test conditions discussed here, the bearing-grade 450FC30 showed lower friction than 450CA30 at the higher PV condition. However, friction depends on the complete tribosystem and should not be generalized to every CF30 or bearing-grade formulation.
There is no universal PV limit for all CF30 PEEK grades. An illustrative continuous dry-PV screening range of approximately 0.2–0.35 MPa·m/s can be derived from the published limiting-PV data discussed here, but actual allowable PV must be determined from grade-specific data and application conditions.
An illustrative continuous dry-PV screening range of approximately 0.30–0.50 MPa·m/s can be derived from the published limiting-PV data discussed here. This should not be treated as a universal allowable rating for all bearing-grade PEEK formulations.
Carbon fiber can contribute to PEEK's tribological performance through reinforcement, transfer-film formation, and improved thermal conductivity. However, carbon fiber is not a substitute for dedicated solid lubricants when low friction is the primary design requirement.
For a bushing that primarily carries structural load and operates at relatively low PV, CF30 may be a suitable starting point. For continuous dry sliding where low friction and wear resistance dominate, a dedicated bearing-grade PEEK is generally the better starting point. The final choice should be validated using the actual counter-face, temperature, pressure, speed, and duty cycle.
Wear and friction data in this article are digitized or derived from the Victrex PEEK Properties Guide, including Figures 30 and 31 for ASTM G137 block-on-ring testing and pages 15–17 for limiting-PV data using a modified ASTM D3702 configuration.
The reported friction coefficients derived from graphical data are approximate.
The grades 450CA30, 450FC30, and WG101 are Victrex grades. PRES CF30 and Bearing Grade are separate PRES formulations and should not be assumed to have identical performance without grade-specific data.
Mechanical properties quoted for PRES CF30 and bearing-grade PEEK are based on PRES reference datasheets.
All values should be treated as typical or reference values for material comparison, not as universal design allowables. Engineers should validate the selected grade under the actual application conditions before finalizing a design.
Rio Liang | High-Performance Plastics Expert
Rio Liang has more than 20 years of experience in PEEK, PPSU, PES, PPS, and PEI material modification and injection-molding solutions, with a focus on engineering material selection and application-specific performance.
For technical questions about PEEK material selection, modified PEEK compounds, injection molding, or wear applications, contact PRES for grade-specific recommendations and datasheets.
