© ElektroPhysik
QuintSonic 7
89 von 184
10.5 Wall thickness measurement
Measuring range: 2 (750 ns).
The same measuring object has been used as in section 10.3. Here, however, not the paint is to
be measured but the wall thickness of the metal base through the paint (coating).
For a start, the basic setting has been used. On the right edge of the A-scan image the so-called
back wall echo can be seen with an amplitude of 13.5%. For that reason, the unwanted echoes in
the middle of the A-scan image can easily be suppressed by setting the upper clipping limits to
8.5% so that only the relevant echoes will be extracted accordingly.
In order to display the wall thickness only, the postprocessor has been set to process the last
echoes (from the rear to the front) only. The number of layers has been set to 1. As a
consequence, the extracted echoes from the paint layers will be marked to be invalid (see fig.) and
thus not taken into account for the calculation of layer thickness.
The sound velocity of “layer “ # 1 that remains after the postprocessing, must to set to the sound
velocity of steel.
Using these settings will then provide the measuring results as shown above.
10.6 Multi-layer plastics foil
Measuring range: 2 (750 ns)
In the above example, a coextruded foil of different materials is concerned. The thickness of the
individual layers varies significantly.
To make sure all echoes will be extracted, the global clipping limits have been set to ±1%.