Theoretical Analysis of Spacing Parameters of Anisotropic 3D Surface Roughness

Abstract

The authors of the research have analysed spacing parameters of anisotropic 3D surface roughness crosswise to machining (friction) traces RSm 1 and lengthwise to machining (friction) traces RSm 2 . The main issue arises from the RSm 2 values being limited by values of sampling length l in the measuring devices; however, on many occasions RSm 2 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=RSm 1 /RSm 2 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.

Experimental Investigation on Roughness Parameters of 42CrMo4 Steel Surface During Nitrocarburizing Treatment

“…Rku the sampling length, in which a profile element is a peak and valley in the surface profile [30]. Table 1 shows the RSm values of the sample's surface before and after the nitrocarburizing process, where it can be seen that the RSm value increased from 13.91 to 24.14 µm with an increase of 74%.…”

Research of Surface Roughness Anisotropy

“…As for the other surfaces, RSm 1 values obtained with the measuring equipment were eligible for usage in calculating c according to formula (1).…”

“…Parameter RSm 2 used in formula (1) When the values of mean spacing of profile elements are obtained, anisotropy coefficient c is calculated according to formula [1]:…”

“…Analysis of surface roughness spacing parameters [1] provides that for surfaces with irregular roughness spacing parameters values occasionally are not reliable due to the fact that mean plane of surface roughness and the roughness profile mean line are located at different levels, in particular, it is expressed for mean spacing of profile irregularities in the longitudinal direction. Thereby difficulties with surface anisotropy evaluation are arising.…”

“…In order to solve the existing problems, scientists offer using the visual method, which will allow identifying more reliable values of spacing parameters RSm 1 and RSm 2 . In addition, it is reasoned that the surface roughness anisotropy can be described by the surface aspect ratio Str from standard EN ISO 25178-2: 2012 [2], which is essentially equal to the roughness anisotropy coefficient c.…”