General Remarks On Measurement - geo-FENNEL FCT1 Data Mode D'emploi

EN
Press blue button to finish calibration. Press button ZERO to save calibration value; alternatively after
30 sec. the instrument will store calibration value automatically.
Note
The instrument calculates the mean of 5 calibration readings furthest. When full, the newest calibration
value will replace the oldest calibration value.
Even while a series of measurements is being taken two-point calibration can be carried out as often as
necessary. The old calibration will be overwritten; the zero-calibration remains in memory.
SHOT-BLASED SURFACES
The physical nature of shot-blased surfaces results in coating thickness reading that are too high. The
mean thickness over the peaks can be determined as follows:
Carry out one-point calibration (see page 25).
Carry out two-point calibration (see page 25).
Use a smooth calibration sample with the same curvature radius as the later measuring sample.
Now take approx. 10 readings on the uncoated, shot-blased sample to produce the mean value Xo.
Thereafter take approx. 10 further readings on coated, shot blasted sample to produce the mean value Xm.
The difference between the two mean values is the mean coating thickness Xeff over the peaks. The
greater standard deviation „s" of the two values Xm and Xo should also be taken into consideration:
Xeff=(Xm-Xo)±s
Note
When calibration is completed the calibration function in the menu should be disabled.
K

GENERAL REMARKS ON MEASUREMENT

After a careful calibration has been carried out all subsequent measurements will lie within the guaran-
teed measuring tolerance.
• Strong magnetic fields near generators or live rails with strong currents can affect the reading.
• W hen using the statistics program for obtaining a mean value it is advisable to place the probe several
times at a typical measuring spot. Any false reading or outliers can be removed immediately via the
menu.
• T he final reading derives from the statistical calculation and from the guaranteed tolerance levels of
the instrument.
• Coating thickness D = X ±s ±μ.
Example
Readings 153μm, 150μm, 156μm -> mean value X = 153μm
Standard deviation s = ±3μm
Measuring uncertainty: μ = ± (1 % of reading + 1μm)
D = 153 ±3 ±(1,53μm + 1μm)
= 153 ±5,5μm
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