Sealey TA090 - Manual (Page 12)

Original Language Version TA090 Issue No.1 25/10/12 © Jack Sealey Limited
14.6.1 Preparing for calibration:
a) Switch the gauge on (keep it away from any metal by at least 10cm).
b) Have substrate sample and necessary foils (calibration standard) to hand.
c) Set work mode i.e. continuous or single via MENU system.
14.7 Zero-point calibration (no need to enable calibration)
14.7.1. Place the probe on an uncoated sample (zero coating thickness) ensuring it is vertical and
stable .
14.7.2.The LCD display will display a value (x.x um). (The operation differs between continuous mode
and single mode. See the work mode section for more details). Then, raise the probe rapidly from the
metal substrate by at least 10cm.
14.7.3. Now press and hold the 'Zero' button for about 1.5seconds, the LCD displays 0.0 um. The
calibration is finished.
14.7.4. Repeat this procedure several times. The calibration system always saves the mean value of
the previous calibration point.
NOTE: You can delete any existing zero point calibration settings not required before making new
zero point calibrations via the MENU system. The gauge always calculates the mean of the latest 5
calibration readings. When full, the newest calibration value will replace the oldest calibration value.
We suggest that you make a Zero calibration when starting a measurement.
14.8 One-point calibration
This method is recommended for high precision measurements, measurements on small parts and on
hardened and low-alloy steel.
14.8.1. Perform a zero-point calibration as described in 14.1.2.
14.8.2. Lay the calibration foil on an uncoated sample, apply the probe and wait for a steady reading.
Remove the probe from the sample & press the UP or DOWN keys to adjust to the required foil
thickness. The thickness of the foil should be roughly equivalent to the estimated coating thickness.
14.8.3. Repeat step 14.8.2 several times to achieve the mean value of previous calibration readings.
14.8.4. Now take readings by placing the probe on the coating and raise it if steady.
It may be necessary to delete calibration, e.g. after entry of a faulty calibration value: (MENU - Delete
- Delete group data). (NOTE: It will delete all data, limit data, one-point and two-point calibrations
except for zero-point calibration).
This will reactivate the default basic calibration for use on even surfaces.
NOTE: The meter calculates the mean of the 5 calibration latest readings. When full, the newest
calibration value will replace the oldest calibration value.
Press the righthand 'bar' key to exit current calibration. Or else, after about 30 seconds, the
calibration will be become effective automatically.
Press Zero button to make current calibration effective.
Even while a series of measurements is being taken, foil calibration can be carried out as often as
necessary. The old calibration will be overwritten; the Zero calibration remains in memory.
14.9 Two-point calibration
We recommend that the gauge is used in single work mode. If necessary switch to this mode using
the MENU system. This method requires the use of two different foils. The thicker one should be, if
possible, 1.5times as thick as the thin one. For best results, the thickness to be expected should be
somewhere between the two calibration values.
This method is especially suitable for taking measurements on rough shot-blasted surfaces or for
high-precision readings. It is advisable to take several readings to acheive a mean value. This
considerably reduces the effect of scattering which occurs during calibration of upper and lower
values.
The calibration foils may be used in any order.
14.9.1 Zero-point calibration according to section 14.1.2
14.9.2 The first point calibration according to section 14.1.3
14.9.3 Repeat the above step .
14.9.4 Take readings by placing the probe on the coating to be measured and raise it after the beep.
The reading is shown on the display.