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mvip@mitech-ndt.com
5.1.3 Surface curvature of the test piece
Make sure that the radius of curvature of the sample surfaces is not less than 30 mm.
The unit can only work properly when the impact body is in a particular position in the guide tube at the
time of impact on the test surface. In the standard position, the tip of the impact body is precisely at the
end of the tube.
Impact device types
Radius
Impact device type G
min
R
=50 mm
Impact device types D/DC, C
and E
min
R
=30 mm
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
