TN_US-BA-e-2020
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high-frequency transducer would be the better choice for detecting small depressions
or impurities in the material.
Geometry of the transducer: The physical limits of the measurement environment
sometimes determine the suitability of the transducer for a particular test object. Some
sounders are simply too large to be used in a fixed environment. If the available surface
for contact with the
sound generator is limited, a sound generator with a small contact area is required.
If a curved surface is measured, e.g. a drive cylinder wall, the contact surface of the
sound generator must also be adapted to it.
Temperature of the material: If measurements are made on unusually hot surfaces,
high-temperature sounders are used. These are built in such a way that they can be
used at high temperatures for special materials and techniques without suffering
damage. In addition, care must be taken when performing a "zero calibration" or
"calibration with known material thickness" using a high temperature transducer.
The selection of a suitable sound generator is often a compromise between different
influences and characteristics. Sometimes it is necessary to select several
to try out sounders until the most suitable one for the test object is found.
The sound generator is the "end piece '' of the measuring instrument.
It transmits and receives ultrasonic waves, which the device uses to measure the
thickness of the material to be examined. The transducer is connected to the gauge by
an adapter cable and two coaxial connectors. When sounders are used, plugging in
the connectors is simple: either the plug fits into the socket or into the instrument itself.
The transducer must be used correctly to obtain accurate, reliable measurement
results.
The following is a brief description of one of these, followed by instructions for use.
The upper figure shows the bottom view of a typical sound generator. The two half
circles are visible, visibly divided in the middle. One of the semicircles directs the
ultrasound into the material to be measured and the other directs the echo back to the
transducer. When the transducer is placed on the material to be measured, it is located
directly below the center of the area whose thickness is to be measured.
The picture below shows the top view of a sound generator.
It is pressed with the thumb or index finger from above on the sound generator to keep
it exactly placed. Only moderate pressure is required, as its surface only needs to be
positioned flat on the material to be measured.
Model
Freq
MHZ
Ø
mm
Measuring range
Lower limit
Description
