Mahr GmbH, MarSurf M 300 and RD 18
20
Selecting the number of sampling lengths
If standard traverse lengths cannot be used with
the testpiece, in accordance with the standard,
the number n of sampling lengths can be re-
duced or increased.
13
If n ≠ 5, the symbol appears in the top status
bar.
By selecting a standard traversing length
with Lt/Lc, the number n of sampling
lengths is reset to 5.
Selecting the cutoff
When evaluating in accordance with ISO, ASME
or JIS, digital filtering generates the roughness
profile from the measured profile.
The phase-correct profile filter (Gaussian filter)
is used. When evaluating the parameters in ac-
cordance with DIN EN ISO 13565-2, the special
filtering method with groove suppression as per
DIN EN ISO 13565-1 is used. The filter is charac-
terized by the cutoff.
The cutoff is the wavelength Lc of a sinusoidal
profile, the amplitude of which will be transmit-
ted by the phase-correct filter to a level of 50 %.
The cutoff defines which elements of the mea-
sured profile will be attributed to the roughness.
The cutoff and traversing length are selected
together before the meas urement by pressing
Lt/Lc.
DIN EN ISO 4288 states that the cutoff for stan-
dard meas urements should be selected as fol-
lows:
for periodic profiles, according to the mean −
width RSm of the profile elements,
and for aperiodic profiles, depending on − Ra
or Rz
(see Table 2).
13 If the automatic setting A of cutoff and traversing length
is set, the number n of sampling lengths cannot be modi-
fied.
If the automatic setting (symbol A) of cutoff
and traversing length is switched on, during the
meas urement the instrument first checks if it is a
periodic profile:
With a periodic profile, the instrument au- −
tomatically sets the standard cutoff and as-
sociated traversing length according to the
RSm value (see Table 2).
With an aperiodic profile, the cutoff and tra- −
versing length are set automatically accord-
ing to the Rz value (see Table 2).
The settings calculated for Lt and Lc are displayed
in the top status bar after the meas urement has
been carried out.
Switching the Ls profile filter on/off
If the Ls profile filter is switched on, the profile
is filtered after the meas urement with a cut-
off wavelength of 2.5 µm or 8 µm (100 µin or
320 µin), depending on the traversing length.
The Ls profile filter can also be switched on and
off in the "Meas uring station" view.
Switching profile inversion on/off
Usually a profile is evaluated in the same way
that it is measured, i. e. profile peaks are also
handled as such.
However, for replica meas urements profile in-
version should be switched on. This causes the
measured profile to be mirrored on the diagram
mean line so that the evaluation is based on a
profile in the correct position.
If a profile is evaluated with profile inversion, the
profile type is displayed in the "Result" view with
a minus sign (e. g. "R–" or "P–").
For the following parameters, the meas-
uring value is affected by profile inver-
sion: Rp, RpA, Rpm, Rv, Rpk, Rk, Rvk, Mr1,
Mr2, A1, A2, Vo, RPc, Rmr, tp, RSm, S,
Rsk, R, AR, Rx, W, CR, CF, CL.
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