This standard specifies the Bockwell hardness test scale A which has the following principle of test.
The test consists in forcing a conical diamond indenter into a test piece in two operations and measuring the permanent increase (e) of the depth of. indentation under specified test conditions. The unit of measurement fcr e is 0.002 mm ; from the measurement of e, a number known as the Rockwell A hardness is deduced,
1 unit = 0,002 mm,