ISO 6508-2:2015 specifies two separate methods of verification of testing machines (direct and indirect) for determining Rockwell hardness in accordance with ISO 6508‑1:2015, together with a method for verifying Rockwell hardness indenters.
The direct verification method is used to determine whether the main parameters associated with the machine function, such as applied force, depth measurement, and testing cycle timing, fall within specified tolerances. The indirect verification method uses a number of calibrated reference hardness blocks to determine how well the machine can measure a material of known hardness.
The indirect method may be used on its own for periodic routine checking of the machine in service.
If a testing machine is also to be used for other methods of hardness testing, it shall be verified independently for each method.
ISO 6508-2:2015 is applicable to stationary and portable hardness testing machines.