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.
Studies on friction and transfer layer: role of surface texture
Friction influences the nature of transfer layer formed at the interface between tool and metal during sliding. In the present investigation, experiments were conducted using “Inclined Scratch Tester” to understand the effect of surface texture of hard surfaces on coefficient of friction and transfer layer formation. EN8 steel flats were ground to attain surfaces of different textures with different roughness. Then super purity aluminium pins were scratched against the prepared steel flats. Scanning electron micrographs of the contact surfaces of pins and flats were used to reveal the morphology of transfer layer. It was observed that the coefficient of friction and the formation of transfer layer depend primarily on the texture of hard surfaces, but independent of surface roughness of hard surfaces. It was observed that on surfaces that promote plane strain conditions near the surface, the transfer of material takes place due to the plowing action of the asperities. But, on a surface that promotes plane stress conditions the transfer layer was more due to the adhesion component of friction. It was observed that the adhesion component increases for surfaces that have random texture but was constant for the other surfaces.
Experimental Characterization of Sliding Friction: Crossing From Deformation to Plowing Contact
A pin-on-disk tribometer was used to investigate the influence of several parameters on the sliding friction coefficient between hard and deformable surfaces. Pits (1045 tool steel) and disk (aluminum 1100) were utilized to simulate the interaction of a harder tool sliding relative to a softer deformable workpiece. Friction coefficient results were obtained at 561 distinct operating conditions by varying the hall diameter (3.18, 6.35, and 12.70 mm), lubricant (oil B, oil A, and grease), sliding speed (0.1∼0.8 m/s) and normal load (50∼1200 g). Several relalionships which characterize the behavior of the friction coefficient as a function of the shear factor, τ k , are established, the importance of these relationships, as related to stamping and forming processes, is discussed.