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mvip@mitech-ndt.com
When concave or convex surfaces are tested, the impact
body either does not entirely leave the test tube or comes
out too far.
Special support rings are available to accommodate
smaller radii on convex or concave surface.
5.2 Triggering the impact
Caution: Incorrect triggering of the impact may lead to incorrect measured values. When the impact is
incorrectly triggered (e.g. the impact device is not correctly positioned), the measured values can be
incorrect.
Arm the unit and trigger the impact in two separate motions. Do not carry out an impact in an area that
has already been deformed by another impact.
Measuring procedure:
Depress loading tube carefully until contact is felt.
Allow it to slowly return to the starting position.
The device is now ready for carry out the hardness test.
Handling of impact device DC: Place the loading stick
adjacent to the test area. Then plunge the face of impact
device (coil side) over the stick and press down until it
reaches the stop position.
Arming
Hold the impact device near the support ring and
place it firmly on the test surface.
Positioning
Trigger the impact by exerting light pressure on the
release button (take care to not compress the spring)
The impact body is released by the catch chunk and
launched onto the test surface with a defined energy. The
result is immediately shown in the selected hardness
scale on the display.
If the indicating device has previously been in standby
mode, it will return to run mode again immediately due
to the measuring process.
Testing
Repeat the procedure for a further impact. After closing the measurement series, the statistics are
automatically calculated and the result is displayed. If a measurement failed, there is a visual signal
(and depending on the warn sound settings an acoustic one).
Note: The measurement series is automatically completed when the currently set number of
measurements per series (average times) is reached. The following measurement is then the first
value of the new measurement series.
5.3 Conversion Deviations
Measurements with a set conversion produce a scattering. The conversion deviation is the variance
resulting from the comparison of measuring values observed with different hardness testing methods. It
includes 2 components. The major share is caused by the fact that there is no clear physical relationship
between the various methods. The second component results from the circumstance that the
comparison of the hardness values (e.g. HL value and Brinell) also includes the measuring deviation of
the method being compared to. Therefore, a conversion between hardness values contains inaccuracies
