coatmaster Flex
Quick 5-minute calibration
A tutorial video showing a quick 5-minute calibration by using a hot air blower for
curing is available on YouTube: https://youtu.be/_RTlbfQXAG4
8.4.16. Offset calibration
For some measurement applications it sometimes occurs that the Flex measurement results
are accurate in one thickness range (usually, the thickness of the calibration sample), but
there is a systematic deviation of the Flex measurement results at lower or higher thickness.
For example, Flex thickness measurements are ok in the range of 80 μm, but we see that
the Flex measures always around 10 μm too high in the range of 40 μm. Such systematic
deviations can occur, for example, if an uncured coating is to be measured with the Flex on
a cured coating. Another situation where such systematic differences arise is when measuring
thin coatings at 10 µm or less.
If the deviation is systematic, it can be compensated with an offset calibration. To make an
offset calibration with the Flex requires at least two calibration samples (in contrast to the
standard application, where minimum one sample is required). In addition, the two samples
must be different in coating thickness at least by a factor of two, in order to provide an
accurate offset determination.
In our example, if we want to make an offset calibration to measure a coating up to 80 µm
thickness, we need one sample with minimum 80 µm coating thickness and a second sample
with maximum 40 µm coating thickness. For each sample, take two reference measurements.
Offset calibration will be active only when these two conditions are satisfied: at least factor
of two between thinnest and thickest coating, at least four reference measurements.
The result of the calibration is displayed in the calibration report (see below)
Calibration report for a standard calibration
(no offset).
Calibration report for an offset calibration,
showing the offset value (in this example -6.3
µm). As a rule of thumb, the absolute offset
value should not be larger than the minimum
coating thickness used in the application. Both
positive and negative offset values are
allowed.
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