Differences in Roughness Parameter Values from Skid and Skidless Contact Stylus Profilometers

Contact stylus profilometry is the leading surface texture measuring method in many manufacturing industries. For years it has been unmatched in terms of accuracy and reliability. Advancements in technology have led to the improvements in the profilometer design. A stylus can either have a built in skid or be skidless. In this study, the influence of skid on the measurement accuracy and repeatability was evaluated. Four different contact stylus profilometers were used to measure three standard roughness artifacts each. Every set of measurements consisted of 50 repetitions of the same profile, with the same parameters. Out of these profiles, five roughness parameters were calculated and were subjected to a statistical analysis. Relative errors of these parameters were also considered and presented individually for each roughness standard. Researchers found differences in the measurement results dispersion of various roughness parameters between the three roughness standards. The presented results of the measurements clearly indicated that there is a dispersion of the obtained values for the older type of contact stylus profilometer (P1, skid). The skidless portable devices, P2 and P3, have better measurement resolution, which results in a noticeably lower dispersion of measured values. A tabletop, stationary device utilizes a skidless measuring probe. It has both the best resolution and the highest rigidity, which results in the lowest dispersion of measured values. The lowest relative error of the Ra parameter was determined for the P2 device (9.2%) and the highest was determined for the P3 device (72.6%).