KERN & SOHN HN-D - Manual (Page 7)

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Instruction Manual
HN-D
HN-D-BA-e-1213 7
2) The shape of the sample surface
Leeb testing principle demands that the velocity of rebound
and impact are on the same line, because the impact body
is moving in a metal tube. Of course, hardness can also be
shown if the velocity of rebound and impact are not on the
same line. In this case, the impact body would collide with
the tube wall when it rebounds, which will affect the
velocity of rebound. This will cause an error on test
accuracy. If the radius of curvature of the sample surface
is smaller, a suitable variant supporting circle has to be
used. We can contribute to design and release those
supporting circles, if needed.
3) The weight of the sample
If the weight of the sample is more than or equal to 5 kg,
testing can be directly started. If it is less than 5 kg, the
sample needs a special charge. The supporting piece has
to be coupled by a coupling medium and pressed onto the
surface of the test piece. By doing this, better test results
will be achieved.
The area of the testing points should be free of vibrations
or shaking. If the weight of the sample is not enough,
supporting, coupling and compressing must be increased
to avoid jitter and sloshing. Shocks should be avoided.
4) The sample stability
Any effective tests need to minimize possible interference
from outside. This is very important for dynamic
measurements, such as Leeb Hardness testing.
Therefore, measurements are only allowed in a stable
hardness testing system.
Appendix 3 Measuring Range
DESIGNED IN REGARD TO THESE STANDARDS:
DIN 50156 (2007 ), ASTM A956 (2006), GB/T 17394
(1998), JB/T 9378 (2001), JJG 747 (1999), DGZfP
Guideline MC 1 (2008), VDI/VDE Guideline 2616 Paper 1
(2002), ISO 18625 (2003), CNAL T0299 (2008), JIS B7731
(2000).
10. Declaration of Conformity