Multi-Layer
Measurement Set-up
on a PosiTector 200 B3 (Advanced)
When measuring a coating
application for the first time, it is best not to guess at
the number of layers. Instead, measure the total thickness
first and examine the graphical display.
Begin by turning graphics
mode ON. Set the number of layers to one (1) so that
the gage reports total thickness. Observe the graphical
display during repeated measurements and note how many “peaks” regularly
appear.
The first measurement taken on this
wood part is 41 microns This low result is caused by
surface echoes. A small triangle points to the dominate
peak that is measured.
Note that two slightly
smaller peaks can be seen lower down representing two
coating layers.
Two adjustments are
required in order to measure the thicknesses of these
two layers.
Step 1:
The first
adjustment is to eliminate the possibility of surface
interference. Using the PosiTector 200’s
menu, the minimum allowable thickness value (Lo Range)
is raised from 13 microns to 113 microns.
With this new Lo Range setting, a
second measurement is taken with a result of 228 microns.
This represents the total thickness of the coating
system. Two strong peaks indicates the gage still detects
two paint layers.
Step 2:
Using the PosiTector 200’s
menu, the number of layers is changed from one to two.
A final measurement reveals the individual
thicknesses of two layers in the coating system.
Note,
the total thickness is still reported as
228 microns.
The top layer is 186 microns and the bottom, primer
layer is 42 microns.
