ATORN DFT
41
Glossary
Calibration method
The calibration method is a predefined calibration procedure. This procedure
determines the measurement accuracy for subsequent measurements. A cali-
bration method consists of one or a combination of both of the following cali-
bration steps:
Calibration step Zero
: Measurement on the uncoated reference part
•
Gage types FE and FE + NF: (display screen NF/FE)
use of the magnetic induction test method
Material needed: Base material = FE = Ferromagnetic reference part from
customer's own production, without the coating to be measured.
•
Gage types FE + NF: (display screen NC/NF)
use of the amplitude-sensitive eddy current test method
Material needed: Base material = NF = Non-magnetic, electrically
conducting reference part from customer's own production, without the
coating to be measured
Calibration step Foil
: Measurement on the calibration foil lying directly on the
uncoated reference part.
•
Material needed: Calibration foils with the desired thicknesses or from
the scope of supply. The circle on the foil marks the specified measure-
ment area.
Calibration standards
•
Uncoated reference part which material has the same properties as the
base material of the sample. Needed for adjustment to the base material
(zero = zero point).
•
Foil with a certain thickness that simulates a coating thickness during the
calibration process. An adjustment to the corresponding coating thick-
ness value is performed for each calibration foil thickness.
•
Calibration standard, coated reference part which base material and
coating material have the same properties as the coated sample and
whose coating thickness has been determined using the most accurate
measurement method possible.
Coefficient of variation V [%]
Percent variation of a
series of measurements
, i. e. standard deviation in terms of the
mean value. V [%] is a characteristic process constant. A sudden change in V [%] indi-
cates a change in process conditions.
