As surfaces for bearing technology become
more and more smooth, conventional techniques such as laser or stylus
profilometry come to their limits for determining surface quality. But slight
differences in surface roughness and structure of bearing components are found
to have immense influence on component life and performance.
Therefore AFM measurements are used to
assess surface quality parameters such as roughness parameters and nanoscale
The images shown below demonstrate that
surface quality of steel balls for wear testing still varies widely depending on
the manufacturer. While on the left the surface is structured by open pores
indicating inferior material quality, the right hand image shows a smooth
surface as demanded by high performance applications.
Mean surface roughness Sa is 21nm and 6nm,
respectively and both balls were sold as the same quality standard.
Figure 1. Steel ball surface testing, 50x50um image, z-range: 150nm, diameter
of ball: 6mm