Grease lubrication in oscillating rolling bearings poses unique challenges — particularly when it comes to starvation, a leading cause of torque fluctuations and wear in applications such as robotics, wind turbine pitch bearings, and precision actuation systems.
A new IMKT publication by Muyuan Liu, Sebastian Wandel, Norbert Bader, Zongyu Lin, Gernot Bayer, Gerhard Poll, and Max Marian titled “Beyond starvation: Amplitude-dependent grease replenishment mechanisms in oscillating rolling bearings” has just appeared in Tribology International (Elsevier):
doi.org/10.1016/j.triboint.2025.111354
The study provides new insights into how oscillation amplitude governs lubrication performance — even more strongly than load or frequency.
Using advanced optical elastohydrodynamic tribometry and bearing-scale experiments, the authors identified three distinct grease replenishment modes depending on amplitude:
- Small amplitudes: Lubrication dominated by grease side bands.
- Medium amplitudes: Cage–side band interaction promotes grease reflow and reduces wear.
- Large amplitudes: Inter-ring grease flow via rolling elements becomes the dominant mechanism.
These findings establish a theoretical and experimental foundation for amplitude-based lubricant selection and design optimization of oscillating bearings, with direct implications for long-term reliability and energy efficiency in electromechanical systems.
