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mvip@mitech-ndt.com
2.2 Impact device D
1,Release button
2,Loading tube
3,Guide tube
4,Coil unit
5,Connection cable
6,Support ring
7,Impact body
During measurement with this hardness tester, an impact body with a hard tip is impacted by spring
energy against the sample to be measured and then rebounds. During the impact, a permanent magnet
integrated in the impact body passed through a coil in which voltage is induced by the forwards and
backwards movement. This voltage is proportional to the velocities. The impact and rebound velocity is
measured when the impact body tip is approx. 1mm away from the sample to be measured. The
measuring signal is converted to the hardness value by the unit electronics, shown in the display and
stored in the unit memory (if set to strore).
2.3 Other impact devices
DC
DL
C
D+15
E
G
The main unit can be combined with any impact device to accommodate specific needs. Special impact
devices are available for use in confined spaces, with special component geometry or surface finish.
2.4 Leeb rebound principle for hardness testing
This hardness tester operates according to the Leeb principle, in which the hardness value is calculated
from comparing the energy of a test body before and after impacting on a sample.
The energy quotient is quoted in the hardness unit HL and is calculated
from comparing the impact and rebound velocities of the impact body. It
rebounds faster from harder samples than from softer ones, resulting in
a greater energy quotient which is defined as 1000×Vr/ Vi.
HL=1000×Vr/ Vi
Where,
HL— Leeb hardness value
Vr — Rebound velocity of the impact body
Vi — Impact velocity of the impact body
