Page 3 - smartWLI roughness

comparability too stylus instruments

periodical nonperiodic profiles sampling length / evaluation length
profiles cutoff
RSm / mm Rz / µm Ra / µm mm mm
ISO 4288 > 0.013 – 0.04 > 0.1 – 0.5 > 0.02 – 0.1 0.08 1.25
0.4
bis 0.1
bis 0.02
0.25
> 0.04 – 0.13
4
> 0.13 – 0.4
2.5
> 2 - 10
> 0.4 – 1.3 > 0.1 - 2 0.8 12.5
> 1.3 - 4 > 10 - 80 8 40

sampling length / cutoff stylus tip radius profile point distance
cutoff low-pass filter max. value max. value
λc / mm λs / µm µm µm
ISO 3274 0.25 2.5 2 0.5
0.5
2
2.5
0.08

2.5
2
0.5
0.8
2.5 8 5 1.5
8 25 10 5

For the evaluation of roughness parameters analogous to stylus instruments, is it necessary to factor in the
characteristics of an ideal stylus instrument (angle and radius of the stylus) as well as criteria for choosing
appropriate parameters (cutoff, sampling length, evaluation length, profile point distance) which depend on
the characteristic of the measured surface (RSm / Rz / Ra).