DeFelsko PosiTector UTG v.2.2 - Manual (Page 10)

The PosiTector UTG allows four simple adjustment
choices. All four methods are based on the simple
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Adjustment
Adjustment, or Calibration Adjustment is the act of
aligning the Gage's thickness readings to match that
of a known reference sample.
The PosiTector UTG is factory calibrated. But in
order for it to take accurate thickness measurements
of a particular material it must be set to the correct
sound velocity for that material. Be aware that
material composition (and thus its sound velocity)
can vary from stated tables and even between lots
from a manufacturer. Adjustment to a sample of
known thickness of the material to be measured
ensures that the Gage is adjusted as close as
possible to the sound velocity of that specific
material. Samples should be flat, smooth and as
thick as the maximum expected thickness of the
piece to be tested.
Cal Settings
micrometer. If the Gage does not measure the
sample within the combined tolerances of the Gage
and the micrometer, the Gage can be adjusted (see
below). For best accuracy this process should be
repeated if the temperature of the part changes
substantially.
To guard against measuring with an improperly
adjusted Gage, verify the Gage at the beginning and
the end of each work shift. During the work shift, if
the Gage is dropped or suspected of giving
erroneous readings, its accuracy should be re-
verified. In the event of physical damage, wear, high
usage, or after an established calibration interval; the
Gage should be returned to the manufacturer for
repair or calibration.