How Friction, Wear & Lubrication Interact - Tribology

Summary

This video features a detailed discussion led by Lake, “The Motor Oil Geek,” alongside tribology and surface metrology experts Dr. Peter Lee (Southwest Research Institute - SwRI), Dr. Donald Cohen (Michigan Metrology), and Dr. Mark Malburg (Digital Metrology). 

The conversation focuses on the critical role of surface roughness and texture in tribology, lubrication, and engine performance, particularly at the piston ring–cylinder liner interface. The panelists explain how surface characteristics influence friction, wear, and lubricant retention, emphasizing the need for a balanced “Goldilocks” surface finish—neither too rough nor too smooth—for optimal efficiency and engine life.

They also trace the evolution of surface measurement technology from basic 2D parameters like Ra to advanced 3D characterization, which allows engineers to design surfaces instead of relying on trial-and-error. The TE77 tribometer is highlighted as a cost-effective method to test real engine parts under realistic conditions, bridging the gap between simple lab studies and full engine dyno testing.

The experts stress the importance of lubricant chemistry working in harmony with surface finish, noting that there is no universal best engine oil. Instead, performance depends on metallurgy, coatings, honing, and operating environment. They also emphasize the significance of the running-in period in establishing stable surface conditions and long-term engine durability. The discussion concludes with forward-looking insights on tribology’s relevance for electric vehicles, bearings, and other applications, as well as opportunities for hands-on training.

Highlights

• ⚙️ Surface roughness and texture critically affect friction, wear, and lubrication in engines.
• 🔬 Advanced 3D surface metrology enables precision surface design beyond simple Ra values.
• 🛠 The TE77 tribometer allows realistic, cost-effective testing of piston ring–liner interactions.
• 🛢 Oil chemistry and surface finish must be considered together—no one-size-fits-all solution exists.
• ⏳ Running-in periods are delicate but essential for achieving stable, optimized conditions.
• 📏 Multi-scale surface analysis (geometry, roughness, atomic-level effects) is vital for accurate diagnosis.
• 🌍 Advances in tribology apply beyond combustion engines, including EV motors and bearings.

Key Insights

• Surface Texture’s Impact: Engine efficiency depends not only on roughness height but also on spatial features. The ideal finish provides contact points and lubricant pockets, reducing friction and wear. Too rough causes abrasion; too smooth causes lubricant starvation.
• From Measurement to Design: Moving from 2D to 3D surface characterization allows engineers to proactively design textures that meet tribological needs, reducing trial-and-error and improving consistency.
• Tribometers as a Bridge: Tools like the TE77 use real engine parts in controlled conditions, offering detailed wear and friction data at far lower cost than full dyno testing.
• Oil Chemistry as Part of the System: Lubricant performance depends on how additives and films interact with surface finish, coatings, and metallurgy. There is no universal best oil—applications dictate the right choice.
• The Role of Running-In: The break-in phase allows surfaces to adapt and stabilize, reducing long-term wear. Advances in honing and coatings can shorten and improve this process, but it cannot be skipped or rushed.
• Scale Matters: Surface interactions occur across multiple scales, from bore geometry down to microscopic roughness and atomic contact. Effective diagnosis requires identifying which scale is driving wear or failure.
• Tribology’s Expanding Frontiers: While developed for combustion engines, tribology principles are increasingly important for EV drivetrains, gears, and bearings, ensuring continued relevance.

Additional Context and Analysis

The panelists highlight how tribology draws from materials science, surface engineering, chemistry, and mechanical design. Traditional roughness parameters like Ra alone are insufficient; spatial data and 3D imaging are needed to understand real-world interactions.

Coatings present a balancing act between hardness, adhesion, and wear resistance. Layered or graded coatings are promising but require precise application and validation. Realistic testing protocols, such as tribometer studies paired with oil analysis data, provide insight into how surfaces and lubricants behave together in service.

The discussion of “Goldilocks” surfaces has direct implications for manufacturing: honing processes must be tightly controlled, as even small variations can dramatically affect performance. This makes advanced metrology tools essential for consistency. The panel also touched on API oil specifications and base oil interchangeability, showing the scale of effort behind standardizing lubricants for diverse applications under both technical and environmental pressures.

Conclusion

This discussion demonstrates how advances in 3D surface measurement, tribological testing, and coating technology are reshaping modern engine design and lubrication. Because surface finish, lubricant chemistry, metallurgy, and operating conditions interact in complex ways, there is no single best solution—only application-specific answers based on rigorous testing. As the automotive world transitions to new propulsion systems, the principles of tribology remain fundamental, ensuring performance and durability in both current and future technologies.