A Comparative Study on the Effect of Surface Topography by Hard Turning vs. Grinding on Frictional Performance at Dry and Lubricated Sliding Contact

Machining-induced surface topography has a significant effect on tribological performance of machined components in sliding contact. However, the effect of different surface topography by turning versus grinding on tribological performance has received very little attention. In this study four types of surface topography by turning and grinding AISI 52100 bearing steel (62 HRc) were prepared and characterized to study its effect on friction and wear in sliding contact. Dry and lubricated reciprocating sliding wear tests with an on-line acoustic emission (AE) sensor were carried out using a ball-on-disk tribometer. The experimental results have shown that: (i) the turned surfaces, regardless of the presence of a white layer, yield smaller friction of coefficients in sliding along feed marks than across sliding at both dry and lubricated conditions. However, the opposite hold true for the ground surfaces; (ii) friction of coefficients (0.6∼0.8) at dry conditions is higher for both turned and ground fresh surfaces than their white layer counterparts regardless of sliding direction. At lubricated conditions, Friction of coefficients (0.1∼0.12) are smaller for the both turned and ground fresh surfaces than the white layer surfaces in along sliding, while it is equivalent in across sliding; (iii) the trends of acoustic amplitude amplitude are consistent with those of frictional coefficients for the turned or ground surfaces at dry conditions. Similar trends are also true for the turned surfaces at lubricated conditions, but not for the ground surfaces; and (iv) the wear debris on the track may act as solid lubricants to reduce the sliding frictional coefficient. Machining induced white layers leads to a better wear resistance than the fresh surfaces in either along or across sliding.