Influence of tilt angle and grinding angle of the plate on friction and transfer layer formation
In the present investigation, unidirectional grinding marks were attained on the steel plates. Experiments were then conducted using pins of high purity Al, pure Mg and Al-Mg alloys against the prepared steel plates using an inclined pin-on-plate sliding tester. The inclination angle of the plate was varied in the tests and for each inclination angle, the pins were slid both perpendicular and parallel to the unidirectional grinding marks direction under both dry and lubricated conditions. Results showed that the friction, transfer layer formation, and the presence of stick-slip motion significantly depend on the grinding marks direction and tilt angle of the hard surfaces under both dry and lubricated conditions for all the three materials investigated.
Effect of Surface Topography on Friction and Transfer Layer during Sliding
Surface topography influences friction and transfer layer formation during sliding. In the present investigation, various kinds of surface topography were produced on steel plates. Pins made of metals (pure Al, Cu and Pb) and alloys (Al-4Mg and Al-8Mg) were then slid against prepared steel plates using inclined pin-on-plate sliding tester to understand the role of surface topography of harder surface and load on friction and transfer layer formation under both dry and lubricated conditions. It was observed that the transfer layer formation and coefficient of friction along with its two components, namely adhesion and plowing, are strongly dependent on surface topography and independent of surface roughness (Ra). The plowing component of friction was highest for the surface that promotes plane strain conditions and lowest for the surface that promotes plane stress conditions near the surface.
Calculation of the fractal dimensions of machined surface profiles
The optimal method calculating the fractal dimension of a machined surface profile is discussed in this paper. Through the analysis of the results calculated by use of the Weiestrass-Mandelbrot fractal function with known fractal dimensions, the variation method is found to be the best one for calculating the fractal dimensions of the surface profiles among the power spectrum method, the cover method and the rectangular cell counting method. By this method, the fractal dimensions of the surface profiles machined by turning, electrical discharge machining and grinding are evaluated. Furthermore, the relation between the fractal dimensions and the machining conditions are also investigated. In the case of turning, the fractal dimensions of surface profiles decrease with the change of the feed rate whereas the nose radius. The fractal dimensions of the electrical discharge machining surface profiles hardly vary with an increase of the peak discharge currents and the pulse durations. The fractal dimensions of the surface profiles machined by grinding do not change with the grain sizes of grinding wheels.