A screening-test-based guide for selecting solid lubricants under low- and high-speed sliding conditions
For buyers sourcing reinforced PA6 / PA66 raw material, wear modification should be evaluated together with stiffness, heat resistance, moisture absorption and molding stability.
This article compares three solid lubricant routes in a 30% glass-fiber-reinforced PA66 compound:
- PTFE
- UHMWPE
- MoS₂
The comparison is based on the supplied screening data. It should be used as an engineering selection reference, not as a universal performance guarantee.
Key Takeaway
Under the stated screening test conditions, 15% PTFE showed the lowest high-speed wear loss in this data set.
For practical material selection:
- PTFE 15%: first route to evaluate when high-speed wear loss is the main concern.
- UHMWPE 6–10%: suitable to evaluate when low-speed friction reduction and higher impact strength are required.
- MoS₂ 2.5%: a low-loading route that retained tensile strength close to the PA66/GF30 baseline and improved measured melt flow in this formulation.
1. Start with the Operating Condition
A single coefficient of friction value is not enough for material selection.
For PA66/GF30, sliding performance is affected by:
- Polymer matrix behavior
- Glass fiber exposure
- Transfer-film formation
- Counterface material
- Surface roughness
- Load and sliding speed
- Temperature and humidity
- Molding quality and fiber orientation
A lubricant that performs well at low speed may not deliver the same result at higher speed. A formulation with good wear resistance may also create trade-offs in density, stiffness, impact strength or melt flow.
2. Formulation and Test Scope
The tested base compound was PA66 with 30% glass fiber.
The lubricant loading levels were:
- UHMWPE: 3%, 6%, 10%
- PTFE: 10%, 15%
- MoS₂: 2.5%
The ring-wear screening test was performed under:
- Load: 30 kg
- Low-speed condition: 0.1 m/s
- High-speed condition: 0.5 m/s
The following results should be interpreted within this test boundary.
| Sample | PA66 | GF | UHMWPE | PTFE | MoS₂ | Antioxidant |
| Baseline | 69 | 30 | – | – | – | 1 |
| UHMWPE 3% | 66 | 30 | 3 | – | – | 1 |
| UHMWPE 6% | 63 | 30 | 6 | – | – | 1 |
| UHMWPE 10% | 59 | 30 | 10 | – | – | 1 |
| PTFE 10% | 59 | 30 | – | 10 | – | 1 |
| PTFE 15% | 54 | 30 | – | 15 | – | 1 |
| MoS₂ 2.5% | 66.5 | 30 | – | – | 2.5 | 1 |
3. Route Comparison Summary
| Lubricant Route | Best Initial Fit | Observed Result in This Data Set | Engineering Notes |
| PTFE | High-speed wear reduction | 15% PTFE showed 16 mg wear loss at high speed | Check density, mechanical retention, molding behavior and market-specific compliance requirements |
| UHMWPE | Low-speed friction reduction with higher toughness | 10% UHMWPE showed COF 0.38 and notched impact strength 13.4 kJ/m² | Higher loading reduced melt flow and tensile strength in this formulation |
| MoS₂ | Low-loading modification with improved processability | 2.5% MoS₂ showed MFR 11.0 g/10 min and tensile strength close to baseline | High-speed wear reduction was limited in this data set; check abrasive wear and counterface effects |
4. Low-Speed Friction Performance
At 0.1 m/s, all three lubricant routes reduced the measured coefficient of friction compared with the PA66/GF30 baseline.
Low-Speed COF Results
- Baseline PA66/GF30: 0.45
- UHMWPE 3%: 0.43
- UHMWPE 6%: value not listed in the supplied text
- UHMWPE 10%: 0.38
- PTFE 10%: 0.37
- PTFE 15%: 0.32
- MoS₂ 2.5%: 0.38
Interpretation
Under the stated low-speed condition:
- PTFE 15% gave the lowest COF.
- MoS₂ 2.5% reached a COF similar to UHMWPE 10%, but at a lower additive loading.
- UHMWPE showed progressive COF reduction as loading increased.
For applications where low-speed friction is the main issue, both PTFE and UHMWPE should be considered. MoS₂ may be attractive where low additive loading and melt flow are important.
5. High-Speed Wear Performance
At 0.5 m/s, wear loss showed a clearer separation between the lubricant routes.
High-Speed Wear Loss Results
- Baseline PA66/GF30: 70 mg
- UHMWPE 3%: 36 mg
- UHMWPE 6%: 30 mg
- UHMWPE 10%: 23 mg
- PTFE 10%: 42 mg
- PTFE 15%: 16 mg
- MoS₂ 2.5%: 55 mg
| Compound | Wear Loss at 0.5 m/s |
| Baseline PA66/GF30 | 70 mg |
| UHMWPE 3% | 36 mg |
| UHMWPE 6% | 30 mg |
| UHMWPE 10% | 23 mg |
| PTFE 10% | 42 mg |
| PTFE 15% | 16 mg |
| MoS₂ 2.5% | 55 mg |
Wear Reduction Versus Baseline
Using 70 mg as the baseline wear loss:
- UHMWPE 3%: about 49% lower wear loss
- UHMWPE 6%: about 57% lower wear loss
- UHMWPE 10%: about 67% lower wear loss
- PTFE 10%: about 40% lower wear loss
- PTFE 15%: about 77% lower wear loss
- MoS₂ 2.5%: about 21% lower wear loss
| Compound | Wear Reduction vs. Baseline |
| UHMWPE 3% | 48.60% |
| UHMWPE 6% | 57.10% |
| UHMWPE 10% | 67.10% |
| PTFE 10% | 40.00% |
| PTFE 15% | 77.10% |
| MoS₂ 2.5% | 21.40% |
Interpretation
Under the stated high-speed condition, PTFE 15% showed the lowest wear loss in this data set.
However, the result should not be applied directly to all applications. High-speed sliding can be sensitive to:
- Counterface material
- Surface roughness
- Heat buildup
- Transfer-film stability
- Glass fiber exposure
- Part geometry
- Contact pressure
- Duty cycle
For high-speed applications, PTFE 15% is the first route to validate, but final selection should be confirmed using the actual mating material and operating profile.
6. Mechanical Properties and Processability
Wear performance is only one part of material selection. For molded PA66/GF30 parts, mechanical retention and processability are also important.
Baseline PA66/GF30
- Tensile strength: 185 MPa
- Notched impact strength: 10.4 kJ/m²
- MFR: 7.9 g/10 min
UHMWPE 10%
- Tensile strength: 164 MPa
- Notched impact strength: 13.4 kJ/m²
- MFR: 2.7 g/10 min
PTFE 15%
- Density: 1.47 g/cm³
- Other listed results indicate relatively higher flow and strength retention compared with high-loading UHMWPE, but detailed values should be confirmed from the original data table before product publication.
MoS₂ 2.5%
- Tensile strength: 184 MPa
- MFR: 11.0 g/10 min
Interpretation
The three lubricant routes create different trade-offs:
- UHMWPE 10% improved notched impact strength but reduced tensile strength and melt flow.
- PTFE 15% delivered the best high-speed wear result in this data set, but density and compliance requirements should be checked.
- MoS₂ 2.5% retained tensile strength close to baseline and improved measured MFR, but its high-speed wear reduction was limited compared with PTFE and UHMWPE.
7. Practical Selection Guide
| Application Requirement | First Route to Validate | Key Items to Test Next |
| High-speed sliding; wear loss is the dominant failure mode | PTFE 15% | Long-term heat aging, counterface wear, dimensional stability, density impact, regulatory and customer requirements |
| Low-speed sliding; lower COF and higher toughness are required | UHMWPE 6–10% | Dispersion, melt flow, stiffness retention, mold filling, shrinkage and warpage |
| Low additive loading; strength retention and better flow are important | MoS₂ 2.5% | Wear scar morphology, noise, third-body abrasion, counterface damage and continuous-run stability |
| Balanced friction reduction with mechanical property control | Compare PTFE 10%, UHMWPE 6% and MoS₂ 2.5% | COF, wear loss, tensile strength, impact strength, MFR and part-level molding trials |
| High-volume injection molding with tight filling window | Start with MoS₂ 2.5% or lower-loading PTFE route | Spiral flow, cavity pressure, short-shot behavior, cycle time and fiber orientation |
8. Engineering Notes for B2B Material Selection
If you are qualifying a modified PA66/GF30 compound for production, it is also important to work with a reliable plastic resin supplier that can provide stable formulation control, technical documents and batch-to-batch consistency.
Test Method Details
- Counterface material
- Counterface surface roughness
- Test standard or internal method number
- Test duration or sliding distance
- Temperature and humidity
- Sample conditioning method
- Specimen geometry
- Repeat count
- Standard deviation
Processing Details
- Compounding method
- Screw configuration
- Glass fiber length retention
- Pellet drying condition
- Injection molding temperature
- Mold temperature
- Injection speed and pressure
- Part thickness
Application Validation
- Actual load
- Sliding speed range
- Peak temperature
- Continuous or intermittent movement
- Lubricated or dry contact
- Counterface wear
- Noise requirement
- Dimensional tolerance
- Regional compliance requirements
9. Recommended Use Positioning
The data are suitable for:
- Early-stage material screening
- Lubricant route comparison
- Internal engineering discussion
- Customer technical communication with clear test boundaries
- Website technical education with a data disclaimer
The data should not be used alone for:
- Universal wear-resistance claims
- Certified product performance guarantees
- Cross-application lifetime prediction
- Regulatory or safety-critical qualification
- Replacement approval without part-level validation
10. Conclusion
Suke Plastics can support custom formulation service for PA66/GF compounds where friction reduction, wear resistance, toughness or processability must be balanced for a specific application.
The main differences are:
- PTFE 15% showed the strongest high-speed wear reduction under the stated 30 kg / 0.5 m/s condition.
- UHMWPE 6–10% provided a useful route for low-speed friction reduction and higher notched impact strength, with a trade-off in melt flow and tensile strength.
- MoS₂ 2.5% offered a low-loading option that retained tensile strength close to baseline and increased measured MFR, but showed limited high-speed wear reduction in this data set.
Final material selection should be validated under the real load, speed, temperature, counterface and molding conditions of the target application.
Data Disclaimer
For commercial approval, these screening results should be supported by proper lab testing and quality control process for plastic resins, especially when wear loss, tensile strength, MFR and impact strength are used in supplier evaluation.
The test results in this article are based on the supplied source manuscript and redrawn data for this project. No missing data were estimated.
The values should be understood as screening test results under the stated conditions, not as universal material performance guarantees.
Actual performance may vary depending on:
- Resin grade
- Glass fiber type and retention
- Lubricant grade and particle morphology
- Additive dispersion
- Compounding process
- Injection molding condition
- Part design
- Counterface material
- Surface roughness
- Load
- Sliding speed
- Temperature
- Humidity
- Duty cycle
- Test method
Before using these results as product claims, the test method, repeat count, standard deviation, counterface details and environmental conditions should be disclosed or verified.
For commercial applications, users should perform part-level testing under actual service conditions.
References / Technical Background
The following references provide technical background on PA66, glass-fiber-reinforced PA66, sliding velocity effects and MoS₂-based tribological modification. They are provided for context only and do not directly certify the specific screening data reported in this article.
- A. Horovistiz, S. Laranjeira, J. P. Davim,
“Influence of Sliding Velocity on the Tribological Behavior of PA66+GF30 and PA66+MoS₂: An Analysis of Morphology of Sliding Surface by Digital Image Processing,”
Polymer Bulletin, 75, 5113–5131, 2018.
DOI: 10.1007/s00289-018-2314-1.
This reference is relevant to PA66+GF30, PA66+MoS₂, sliding velocity and tribological behavior. (hero.epa.gov) - Y. Zhou et al.,
“Tribological Applications of MoS₂-Reinforced Polymer Composites: A Review,”
Polymer Composites, 2026.
DOI: 10.1002/pc.71282.
This review is relevant to MoS₂-reinforced polymer composites and tribological applications. (4spepublications.onlinelibrary.wiley.com) - R. Autay, A. Njeh, F. Dammak,
“Effect of Thermal Aging on Mechanical and Tribological Behaviors of Short Glass Fiber–Reinforced PA66,”
Journal of Thermoplastic Composite Materials, first published online 2018.
This reference is relevant to glass-fiber-reinforced PA66 mechanical and tribological behavior under aging conditions. (journals.sagepub.com) - A. V. L. R. Carvalho et al.,
“Temperature, Pressure, and Velocity Influence on the Tribological Properties of PA66 and PA46 Polyamides,”
Materials, 2019, 12, 3452.
This reference is relevant to the influence of temperature, pressure and velocity on polyamide tribological behavior. (pmc.ncbi.nlm.nih.gov)
