A list of key metrics:
- Enduring high-pressure contact situations
- Treatment of non-rotationally symmetrical geometry
- Compatible with super-finishing equipment
The camshaft plays a vital role in internal combustion engine. Synchronized with the crank shaft, it sets the valve timing for optimal engine performance.
With the continuing trend toward increasing fuel injection pressures, Hertzian stresses on the valvetrain has grown to the point that cam lobe contact fatigue has become a critical issue for engine durability, especially for fleets with frequent engine starts and shutdowns. Contact fatigue affects both the injector lobes and the exhaust and inlet lobes. A high pressure contact situation also contributes to valvetrain friction, another important issue impairing fuel economy.
Triboconditioning is a potent tool for enhancing the tribological properties of camshafts, especially well suit for mechanical bucket tappet valve trains. Depending on engine design, Triboconditioning can be performed in two different area of the camshaft: on the bearing surfaces and on the cams.
ANS triboconditioned camshafts much better endure high load situations, when the cam pushes a valve with a force of nearly 20 kN, resulting in Hertzian contact pressure in the range of 3.5 – 4.0 GPa, and allow one to reduce valvetrain friction by upto 30%, thus improving fuel economy. The greatest friction-reducing effect is observed at low engine speeds (heavily charged engines), high oil temperatures, and in combination with thinner engine oils of SAE 20 and SAE 30 viscosity grades.
Effect of ANS triboconditioning on valvetrain friction measured using a motored cylinder head friction rig (after B. Zhmud et al., Application of mechanochemical surface finishing for improving the tribological properties of valve train components, VDI Conference “Ventiltrieb und Zylinderkopf 2012”, November 27-28, 2012, Würzburg, Germany).