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Portable Hardness Testers - Types
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Portable Rockwell Hardness Testers
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Portable testers are needed when a
Rockwell hardness test is specified on parts that do not readily lend themselves
to testing on conventional "bench" testers, and when the cost of a "bench"
tester cannot be justified. Typical applications for these instruments
vary from machined steel parts to the extruded aluminum sections used in
aircraft construction and tubes used for bicycle frames. Both of the
Rockwell testers listed in this guide provide
direct, true Rockwell Readings without calculations or conversion tables. The
indentations made by these testers are of the correct shape and
depth.
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Portable Brinell Hardness Testers
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Portable Brinell hardness testers are
most often used to test castings and forged materials that are too big for
conventional testers. Typical applications for these testers include
the testing of plate, pipe, pressure vessels, casting, rails, axles and other
large or installed components. Brinell tests are required on materials with
course grain structure which would cause inconsistent readings from a Rockwell
tester. Brinell testing is more tolerant of surface of surface
roughness than any of the other hardness testing
methods.
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Portable Dynamic Hardness Testers
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Dynamic testers work by comparing the
speed that an indentor strikes an object to its rebound velocity. The ratio of
these values is a measurement of the material's hardness. The instrument then
converts the ratio to a conventional hardness value in Brinell, Rockwell B or C
as selected. Conversions use generalized tables developed for many common
materials and alloys. This test method is covered by ASTM A956-96.
Dynamic testers are popular due to their speed, convenience and ease of use.
They work best on heavy applications such as large and thick castings, forgings,
axle shafts, rails, etc. Parts weighing less than 6 pounds and under 3/8" thick
must be supported to get an accurate test.
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