Effect of surface roughness parameters and surface texture on friction and transfer layer formation in tin–steel tribo-system

Surface texture of the tool is one of the most influential factors that affect friction at the interface during metal forming operation. In the present investigation, experiments were conducted using a pin-on-plate inclined sliding tester to study the effect of the surface texture of the tool on the coefficient of friction and the transfer layer formation in tin–steel tribo-system. 080 M40 steel plates were ground to attain surfaces of different texture with varying roughness. Pins made of pure tin were then slid against the prepared steel plates. Scanning electron micrographs of the contact surfaces of pins and plates were used to reveal the morphology of transfer layer. It was observed that the coefficient of friction, formation of transfer layer, and the presence of stick–slip motion depend primarily on the surface texture of tool surfaces, and independent of surface roughness (Ra) of tool surfaces. However, it is seen that a single surface roughness parameter, namely, average slope of the profile, ‘Del a’, of the tool surface plays an important role in determining the frictional behavior of the surfaces studied. The effect of surface texture on coefficient of friction was attributed to the variation of plowing component of friction, which in turn depends on the average slope of the profile.