The intersection of the workpiece surface with a plane normal to that surface and in a direction that maximizes the surface roughness value—typically at a right angle to the lay of the machining marks—results in the actual profile.

The profile that is measured is the one that is obtained from scanning the real profile with a probe that mechanically filters it based on the radius of the tip of the probe (Rtip) and, if used, the skid of the probe system. Surface flaws like cracks, scratches, and dents do not belong in the profile and are not appropriate to record. Tolerances in accordance with DIN EN ISO 8785 may be established for them, if necessary.

The roughness profile (R-profile) is the principal profile that has been electronically highpass filtered with a cut-off wavelength of λ c. As seen in Figure 2, this procedure eliminates the longer wavelength components. The evaluation length ln, which typically consists of five sampling lengths lr, is where the parameters with the designation R are evaluated. The profile filter’s cut-off wavelength, λ c, and sampling length are related.

NextGen’s NG-SR400T Surface Roughness Tester tolerance is ±(5nm+0.1A) A=Ra standard value of precise specimen.

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