Salutron HardyTest HARTIP 1800, Руководство по эксплуатации

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with impact device D/DL the depth of the hardened layer should be no less than 0.8 mm.
5.4. Surface of the test sample should not be magnetic.
5.5. For test sample of curving surface with radius of curvature R less than 30mm, a
small support ring should be used.
5.6. Supporting the Samples during Testing
Type of impact device
Classification of samples
heavy medium-weight light-weight
D/DL more than 5 kg 2 - 5 kg 0.05 - 2 kg
When measuring hardness with this tester, the following has to be noticed: Despite the
low mass of the impact body and low impact energy, a relatively large impact force of
short duration is generated when the impact body hits the measuring surface. The max.
impact force of impact device D/DL is 900N.
For heavy samples of compact shape, no particular precautions are necessary.
Smaller and lighter samples or work pieces yield or flex under this force, producing
L-values which are too small and of excessively large variation. Even with big or heavy
work pieces it is possible for thin-wall regions or thinner protruding parts to yield upon
impact. Depending on the frequency of the resilient yielding action, the measured L-value
may be too small or too large. In many situations, potential problems can be checked in
the following manner:
a) Medium-weight samples and also heavier samples with protruding parts or thin walls
should be placed on a solid support in such a manner that they do not move or flex during
the test impact.
b) Light-weight samples should be rigidly “coupled” with a non-yielding support such as a
heavy base plate. Clamping in a vice is of no value, since the samples become exposed to
stress and because complete rigidity is never attained. As a rule, the measured L-values
would be too small and show excessive variations.
5.7. Samples with Curved Surfaces
Impact testers only work properly, if the impact body has a certain position in the guide
tube at the moment of impacting the test surface. In the normal position, automatically
present when testing flat and convex-cylindrical samples (such as round samples), the
spherical test tip is located exactly at the end of the guide tube.
However, when testing spherically or cylindrically shaped concave surfaces, the impact
body remains further within the guide tube or protrudes further therefore. Thus, with
such types of curved surfaces, it is to be observed that radii of curvature do not drop
below the values indicated in the following Fig.
Curved surfaces should always be tested with the small support ring.
Impact device types D R
min
=30mm
For impact devices D, special support rings are available to accommodate smaller radii on
convex or concave surface.