Effect of Running-In (Load and Speed) on Surface Characteristics of Honed Gears

Abstract

The initial running-in cycles alter the surface integrity characteristics and influence gear performance. This article shows how the surface characteristics of honed spur gears evolved due to the combined effect of running-in load (0.9 or 1.7 GPa) and speed (0.5 or 8.3 m/s) in Forschungsstelle fur Zahnräder und Getriebebau tests. Running-in affected the surface layers to a depth of 5 µm. High running-in load promoted plastic deformation of asperities, created microstructural changes associated with surface cracks, and relaxed residual stresses. It also enhanced the amount of phosphorous from extreme pressure (EP) additives at the surface. The surface contact fatigue failure—that is, micropitting—was promoted by running-in speed rather than load.

Keywords:

• Running-in
• surface integrity characteristics
• honed spur gears

Acknowledgements

This work was done in cooperation with AB Volvo and Scania CV AB. The authors thank Professor U. Olofsson at the Royal Institute of Technology for valuable discussions and support. We also thank Edwin Bergstedt for helping us with the roughness measurements.

Additional information

Funding

The authors gratefully acknowledge financial support of the Swedish Agency for Innovation Systems (Vinnova).