It is hard to imagine present-day hardness testing machines without automatic evaluation of hardness indents. It dramatically reduces operator influence in hardness tests and improves the comparability of results.
A hardness indent is evaluated automatically in depth measurement methods by means of a depth measurement sensor in combination with the test software. The depth measurement gauge determines a depth differential during the indentation process with the indenter. Then the test software uses this differential to immediately calculate the hardness value automatically. Following indentation, the determined hardness value is shown on the display of the hardness testing machine.
With automatic evaluation of optical test methods, the measurement result is determined by the interaction between camera system and test software. Here the camera system positions the measuring lines for the indent's two diagonals automatically after indentation. This is achieved through automatic detection of the light/dark difference between indent and test part surface. As soon as the camera system has applied the measuring lines, the test software uses the determined diagonal values to automatically calculate the hardness value. After indentation and optical evaluation, the calculated hardness value is shown with an indent image on the display of the hardness testing machine. Fully automated evaluation of a hardness test indent prevents any operator influence through incorrect positioning of measuring lines.