Hard facts
Calibration and standards
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A direct verification of the hardness testing machine directly checks all measurement variables used for determining the hardness value. The measurement equipment used for this must be properly traceable to national standards. In practice, direct verification is performed as part of calibration by an accredited calibration lab (service provider.)
Depending on the method, the following measurement variables of the testing device are checked:
- Test force
- Indenter geometry
- Measurement system (depth measurement system or measurement system for determining the indentation diameter)
- Test cycle
Direct verification must be performed prior to initial commissioning of a hardness testing machine, after repairs and modifications, as well as whenever indirect verification fails. Direct verification is also required if the most recent indirect verification was performed outside of the cycle defined in the standard.
