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5.11 Selecting probes
Probe
Frequenc
y
Measuring range
Min. area
Application
5P
10
5MHz
1.0mm~300.0mm
(steel)
20×3mm
General
Straight probe
5P
10/90
General bent probe
7P
6 300 7 MHz
0.75mm~25.0mm
(steel)
15×2mm
thin work piece
ZW5P
10 5 MHz
0.75mm~25.0mm
(steel)
30mm
high temperature
2P
14
2 MHz
3
．
0mm~300.0mm
(steel)
20mm
casting work piece
5.12 Changing probe
The wear
of the probe’s interlayer plate will influence the measurement.
Please replace probe when the following situation happens.
1.
When measuring different thickness, it always displays the same
value.
2.
When plugging the probe, it has echo indication or measured value
display without measuring.
5.13 Measuring casting
It has specialty for measuring casting. The crystal particles for castings are
coarse, the structures are not dense enough, plus that they are in gross
state, which makes difficulty in measuring their thickness.
First of all, due to coarse crystal particles and not-so-dense structure, it
will cause large attenuation in sound energy. The attenuation is due to
material’s scatte
r and absorption of sound energy. The attenuation
degree is closely relative with the size of crystal particle and ultrasonic
frequency. Under the same frequency, the attenuation will increase with
the crystal diameter, but it has a high limit, when it reaches to this limit, if
the crystal diameter increases, the attenuation will tend to be a fixed
