First
specimen to come in contact, first with the pressure foot
and later with the indenting tip under the specified contact
load. Further movement of the platform causes the indenting
load to act on the test specimen. Penetration of the indenting
tip into the test specimen is determined with the help of
a dial gauge fitted at the top of the pressure foot assembly.
The contact between the dial gauge and the top of the plunger
rod is made through an electrical arrangement to ensure that
the weight of the stem of the dial gauge does not act on the
test specimen. An electric buzzer is provided to slight vibrations
to the plunger rod to eliminate friction. The dial gauge gives
the depth of indentation in units of 0.01 mm which can be
converted into IRHD hardness value.
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