Theoretical Analysis of Spacing Parameters of Anisotropic 3D Surface Roughness

The authors of the research have analysed spacing parameters of anisotropic 3D surface roughness crosswise to machining (friction) traces RSm₁ and lengthwise to machining (friction) traces RSm₂. The main issue arises from the RSm₂ values being limited by values of sampling length l in the measuring devices; however, on many occasions RSm₂ values can exceed l values. Therefore, the mean spacing values of profile irregularities in the longitudinal direction in many cases are not reliable and they should be determined by another method. Theoretically, it is proved that anisotropic surface roughness anisotropy coefficient c=RSm₁/RSm₂ equals texture aspect ratio Str, which is determined by surface texture standard EN ISO 25178-2. This allows using parameter Str to determine mean spacing of profile irregularities and estimate roughness anisotropy.