Table 7: Average values (computed over the four procedures) and standard deviation of roughness Ra measured in the experi-mental tests. Statistical comparisons (Tukey post-hoc test, Control Group A) are shown in the last column.

A [mm] B [mm] C [mm] D [mm] Comparison vs A
mean 1.253 0.533 0.955 0.513 B, D
Std dev 0.535 0.401 0.449 0.316