Developments in Australia's surface roughness measurement system

Roughness standards in Australia are established, maintained and disseminat ed by the Melbourne Branch of the National Measurement Laboratory (NML), Co mmonwealth Scientific and Industrial Research Organisation (CSIRO). A Taylor Hobson Talysurf 3 stylus instrument has been upgraded by replaceme nt of the original valve amplification with solid-state electronics and the implementation of Windows 95 based software for profile analysis. The ampl ification is calibrated using gauge blocks wrung onto an optical flat or wi th master groove standards, calibrated using an interference microscope wit h a helium-neon laser light source. Measurements of step height or peak-to- valley roughness height in the range 0.1-50 mum are possible. The stylus instrument interfaces directly with a PC via a high speed analog ue-to-digital card. Software has been developed to analyse grooves and step s and to characterise surfaces by calculation of various parameters such as arithmetic mean deviation (R-a). Typical uncertainties are better than 4% at a confidence level of 95% and are calculated automatically by the softwa re according to the ISO "Guide to the Expression of Uncertainty in Measurem ent". Technical and administrative procedures are discussed in the context of acc reditation within the National Association of Testing Authorities, the Aust ralian laboratory accreditation organisation. The facility has participated informally in a regional Asia-Pacific Metrolo gy Programme intercomparison in which three surface roughness and two groov e standards were circulated and the results are discussed. Using historical data, alternate traceability routes, and various artefact chains, the integrity of surface texture measurement at the new facility ha s been evaluated and verified. (C) 2001 Published by Elsevier Science Ltd.