Mitech MHRS-150 Digital Rockwell Hardness Tester
Overview
Mitech MHRS-150 Digital Rockwell Hardness Tester, based on the
mechanical principle of conical diamond or hard alloy indenter
pressing into the sample surface to produce indentation, realizing
the material hardness measurement by measuring the depth of the
indentation. Capable of inspecting the finished or semi-finished
parts of the machined sample, it is suitable for high accuracy
hardness testing for batches parts with various metal or
non-metallic materials. According to statistics, Rockwell hardness
testing is the most widely used hardness testing method in metal
processing industry, which utilization ratio is more than 70%. With
novel appearance, stable performance, intuitive and convenient LCD
display, and easy to operate the menu design, it is widely used in
metal processing and manufacturing, various metal material’s
failure analysis and other fields like colleges and research
institutions. It is the new type Brinell hardness testing
instrument for testing the hardness of the materials like cast
iron, steel, soft alloy and so on.
Working Principle
The Rockwell hardness test is taking the diamond cone with 120°apex
angle or the hardened steel ball with specified diameter as the
indenter to press into sample surface with specific test force,
then get the Rockwell hardness of the measured metallic materials
according to the sample surface indentation depth.
The Rockwell hardness measurement principle is shown as below
figure. 0-0 is the position that the diamond indenter is not yet in
contact with the sample. 1-1 figure is the indenter position under
the affect of the preliminary test force, the indentation depth is h1. The preliminary test is to eliminate the influence to the testing result accuracy
caused by the roughness of the sample surface. 2-2 in the figure is
the indenter position under the influence of the testing force (the
preliminary test force and the main test force). The depth is h2.
3-3 in the figure is the indenter position after dismounting the
main test force. As the metal elasticity will recovery some degree
after deformation, the really indentation depth of the indenter is
h3. The plastic deformation caused by the main test force make the
indenter pressing into the depth is h=h3-h1. Rockwell hardness
value is determined by the size of h, the greater the depth h, the
lower the hardness, otherwise, the higher the hardness.
In the traditional concept, usually use a constant C minus h to
represent the level of hardness, while the depth of indentation per
0.002mm as a unit of hardness. The hardness value obtained is
called the Rockwell hardness value, denoted by the symbol HR.
In the formula, c is a constant (for HRC, HRA, c is 0.2; for HRB, c
is 0.26). The Rockwell hardness value HR obtained is an unknown
number which is usually read directly on the test machine indicator
when testing.
Rockwell hardness tester working principle Figure
It should be noted that the measured hardness values would be
different with different indenter and test force. Therefore, the
Rockwell hardness testing specifies 15 different hardness test
scales according to the different indenter specification and test
force sizes. And the HRB, HRC, HRA are the most widely used.
Features
- Widely used for high-precision hardness testing for parts with a
variety of metal and non-metallic materials;
- Option for various specifications of the indenter, support 15 types
of Rockwell hardness scales testing;
- Equipped with high-speed thermal printer, it can quickly print out
the test data;
- Support the conversion among various hardness scales such as
Brinell, Vickers and etc;
- Adopt large-screen LCD, easy to operate, visually display the test
results;
- Adopt diamond indenter, durable and accurate measurement;
- Use grating displacement sensor, and the indentation depth
measurement error is small;
- With the error value correction function, the hardness value of the
error can be corrected by key input, making the hardness value more
accurately meet the test requirements;
- With the function of threshold overrun automatic alarm, which
applies to the bulk of finished products or semi-finished pieces of
paper-by-piece detection;
- The function of original ambient temperature real-time display can
avoid the instrument working in the case of high or low temperature
for a long time , resulting in increased test error and reducing
the service life;
- Consistent with EN-ISO-6508,GB/T230.1,GB/T230.2,JJG112,ASTM E18 and
other relevant standards at home and abroad.
- The test personnel should follow the operating procedures.Before
and after the test,it should be repeated with standard block
calibration equipment;
- If the specimen has visible deformation marks on the back and
edges, the test result would be useless. It should choose the
intender or test force to test again;
- Normally, the first point is only used to offset the gap of each
support surface without needing to record the test result. Record
the statistical test result from the second point;
- During testing, to ensure accuracy, please make sure the distance
between the adjacent indentation center and the distance from the
indentation center to edge of the specimen is greater than 3mm;
- Pay attention to palm the instrument for carrying to forbid falling
across. Please fix well the measuring lever, counterweight and boom
before carrying;
- It is strictly prohibited to turn the variable loading handwheel
when the instrument load or unload the test force. Rotating the
handwheel forcibly will cause the internal gear dislocation, test
force in chaos and even damage the internal parts of the
instrument;
- Turn off the power after using the instrument;
- When not in use for a long time, please cover the dust cover to
prevent dust into the instrument interior. And the hardness block,
indenter should be coated with antirust oil to prevent rusting
after using;
- Long time after the re-enabled,it should be preheated the
electrical components before test
- The hardness tester should be calibrated at least once a year to
ensure its accuracy;
- Don’t disassemble the instrument without authorization, for
maintenance related matters, please contact MITECH after-sale
service department with 4000600280