Ada ZCT AUTO, Operating Manual, Page: 12 / 40

MEASUREMENT FOUNDATION
ZCT AUTO
12
4) Curvature
The curvature of the test piece has impact on the measurement. This kind of impact will always increase signiicantly with
the reduction of curvature radius.
5) Surface roughness degree
The surface roughness degree of basal body metal and coating has impact on measurement. As the roughness degree in-
creases, so does the impact. The rough surface will cause system error and accidental error. For each measurement, the num-
ber of measurement should be increased on different locations in order to overcome such accidental errors. If the basal body
metal is rough, it is a must to determine several positions on test piece of basal body metal which is uncoated with similar
roughness degree to calibrate the zero point of the instrument. Or calibrate the zero point of the instrument after remove the
coating with the solvent which is not corrosive on the basal body metal.
6) Magnetic ield
The thickness measurement by magnetic property method will be seriously affected by the strong magnetic ield produced
by a variety of electrical equipments around.
7) Attached materials
The instrument is sensitive to those attached materials which hinder the close contact between measuring head and the sur-
face of coating. Therefore, the attached materials must be got rid of to ensure that the instrument measuring head can come
into direct contact with the surface of test piece.
8) The pressure of measuring head
The pressure which measuring head places on test piece will affect measurement readings. Therefore, the measuring head
of this instrument maintains basically constant pressure by spring.
9) The position of measuring head
The position of measuring head has impact on measurement. The measuring head should be perpendicular with the surface
of sample during the measurement.