International comparison of surface-texture parameters organized by the Asia-Pacific Metrology Programme

This paper reports on an international comparison of surface-texture parameters, Ra, Ry5 and Ry, carried out between nine national metrology institutes from 1996 to 1998 under the auspices of the Asia-Pacific Metrology Programme (APMP) and coordinated by the CSIRO National Measurement Laboratory (NML, Australia). The results show that the consistency of the Ra measurements is generally better than that of the Ry5 and Ry measurements, which appear to split into two sub-groups with some crossover. Agreement is somewhat better for artefacts of higher surface roughness. Measurements of step height were also made as a potential indicator of correlation between the basic length scale and the surface-roughness parameters. These show satisfactory agreement, within the stated uncertainties and with the normalized error, En, values < 1 in all cases.