Abstract: A cam follower with a roller for use with an engine, the roller adapted for rolling contact with a cam on a camshaft. The roller is formed with minute recesses arranged in random directions so that an RMS(L)/RMS(C) ratio is not more than 1.0 wherein RMS(L) and RMS(C) are surface roughness root mean square values in the axial and circumferential directions, respectively. An SK value, another surface roughness parameter, should be not more than -1.6. This degree of roughness represents a higher surface roughness than prior art cam followers, provides greater oil retention and therefor better lubrication.

Abstract: A machine part having a rolling or sliding surface formed with a plurality of minute recesses at random with the SK value less than zero in both the longitudinal and circumferential directions, and the area ratio of the recesses to the whole rolling surface being 10-40 percent.

Abstract: A roller element for use in a roller bearing having a surface formed with minute recesses at random so that the ratio RMS(L)/RMS(C) will be not more than 0.8 wherein RMS(L) is the roughness mean square value in the longitudinal direction and RMS(C) is the roughness mean square value in the circumferential direction and so that the SK value is not more than -0.2 in both the longitudinal and circumferential directions.