13.
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11.3 Readjusting the factory zero-point
With any calibration method including a zero reference point, a so-called correction for geometry is
carried out when taking the zero reference point. The geometry correction determines the surface
curvature of the sample by identifying its deviation from curvature at the zero-point of reference
standard and a correction of the complete sensor characteristics is carried out accordingly. That’s
why in most cases, a zero-point calibration will prove to be sufficient. For using this correction
method, it is required that the gauge is set to the factory pre-settings and no deviations can be
observed and when taking zero-point measurements on the test sheets supplied with the gauge.
When taking readings on the test sheets, zero should be shown as precisely as possible. This is
usually the case.
If deviations from zero-point are higher than specified on the respective sensor data sheet (i.e.
higher than the fixed proportion of specified tolerance, i. e. 1.5µm with the FN5 sensor), it is
recommended to readjust the factory set zero-point.
Readjustment is made in the sensor service menu. This is available
in English only and can be accessed via the sensor data menu.
Select view sensor data and press the following keys subsequently:
arrow up and menu key. Press OK to confirm.
Select ”Initial-Zero“ form the sensor service menu.
If a dual sensor is connected, i.e. the FN 1.5/0.7, a menu to select
the measuring principle will appear.
Choose the measuring principle (for ferrous or non-ferrous) for
which you would like to take the zero measurement.
The readjustment must be carried out very carefully. Please use a
blank and smooth substrate. Remove any residues of grease or oil,
metal cuttings or other if necessary from the substrate or sensor
pole. Any foreign matter will distort calibration. Please refer also to
section 6.1 for general remarks on calibration.
Carry out calibration according to 6.2.2.1. After pressing OK, a
security prompt appears to ask you whether to replace the factory
pre-settings by you current zero-point readjustment.