A comprehensive characterization of 3D surface topography induced by hard turning versus grinding

Surface topography induced by precision machining is critical for component performance. Four representative surface topographies of turned and ground surfaces were prepared at “extreme” machining conditions (gentle and abusive) and compared in terms of 3-dimensional (3D) surface features of amplitude, area and volume, spatial, and hybrid parameters. The 3D surface topography maps revealed the anisotropic and repeatable nature of a turned surface which was in sharp contrast with the random and isotropic nature of a ground surface. In general, a gentle turned surface has higher values of amplitude parameters (arithmetic mean, root mean square, maximum height of summits, maximum depth of valleys, and 10-point height) than an abusively turned surface, whereas the opposite was true for the ground counterparts. Only the gentle ground surface has a negative skewness which means that the topography distribution is more biased towards the valley side. The larger kurtosis value of the abusively ground surface implies a more peaked surface topography. The gentle ground and abusively turned surfaces have a much larger bearing area ratio and therefore better bearing capacity than the gentle turned and abusively ground ones. The abusively ground surface has higher fluid retainability than other surfaces in terms of mean void volume. However, surface performance, such as wear and fatigue is dependent both on surface topography as well as mechanical property and relies on the dominance of the individual aspect.