The effect of stylus tip radius on Ra, Rq, Rp, Rv, and Rt parameters in turned and milled samples

This study aims to investigate the effect of the stylus tip radius factor on the values of roughness parameters (Ra, Rq, Rp, Rv, and Rt) obtained by an electromechanical surface roughness tester. The study was based on a single factorial design, where the stylus tip radius was investigated in two levels (2 μm and 5 μm). The roughness measurement was carried out in samples of SAE 1020 carbon steel and gray cast iron, obtained by turning and milling processes for different cutting conditions. During the turning and milling processes, the cutting depth assumed 0.5 mm and 1.0 mm values; and the feed rate was equal to 0.1 mm/rot and 0.2 mm/rot. The uncertainty associated with the measurement of all the evaluated parameters was estimated by applying the GUM method. The analysis of variance (ANOVA) was applied, and it was observed that the stylus tip radius factor did not cause statistically significant effects on the Ra, Rq, Rp, Rv, and Rt parameter values for 54 % of all evaluated conditions. However, the differences between the Ra, Rq, Rp, Rv, and Rt average values obtained using 2-μm and 5-μm radius stylus tips were lower than the values of the associated expanded uncertainty (95 %) in 82 % of performed experiments.