Surface roughness calibration services of sixteen countries from four metrology regions are compared through measurements of roughness and step height standards. The artefacts circulated include three steps of nominal depths 0.4 μm, 2.4 μm and 10 μm, whereas the roughness sections of both type C and type D profiles have nominal Ra values of 0.2 μm, 0.95 μm, 1.5 μm and 3.1 μm. Two softgauges were also circulated for comparison of software independent of hardware. For the steps, parameter d is reported, while for the type C and type D standards and softgauges, 14 different roughness parameters are reported between them. Concluding measurements from the pilot in general show good standard stability, however for some parameters on the artefacts of larger roughness, stability is less certain and this may be an issue in some poor results from the last few laboratories in the schedule. For each parameter, a key comparison reference value (KCRV) is determined using a weighted mean with outliers excluded based on the Birge ratio method until all accepted values form a statistically consistent population. For the 5 artefacts, out of thirty-five separate parameters, only ten have good agreement of all submitted results. Where some parameters had to be excluded from the KCRV, some laboratories had consistent problems with particular types of parameter over the different artefacts, while for other laboratories the issues seemed to be random. Comparison of softgauge results and artefact results has proven to be inconclusive.
Citation: Bureau International des Poids et Mesures
Issue: Tech Suppl.
Pub Weblink: http://www.bipm.org
Pub Type: Websites
surface, roughness average, step height, depth, softgauge, calibration, stylus, radius, comparison