Roughness Metrology: Conversion of profiles from measurements with reference plane profilometers into skidded probe profiles : Expert report DKD-E 4-2

This expert report presents a procedure for the calibration of roughness standards used to represent the surface quality of sheet metal, which makes it possible to dispense with the use of double-skid probes during calibration. When using this procedure, profiles acquired with reference plane profilers are converted into skid probe profiles. This is relevant for the maximum height parameters, Rz, Rzmax und Rzx . For thin sheets with typical Rz values in the range of 5 µm to 5,5 µm, the results of skid and reference plane profilers differ by approximately 0,6 µm. The uncertainty of the skidless to skidded transformation procedure is approximately 0,1 µm. There is no significant change in the values when determining the arithmetic mean height Ra and the peak value RPc or Rpc , so there is no need to convert those values. The skidless to skidded transformation method helps to reduce time needed for modification and adjustment of the measuring set-up, and it eliminates uncertainty components due to form and position tolerances of the double-skid probes. Reduction of the smallest accredited measurement uncertainties is therefore recommended.