Sauter hmm leeb hardness meter sauter hmm p when a hardness test is carried out by the sauter hmm leeb hardness meter an impact body with a tungsten carbide test tip is propelled by spring force against the surface to be tested from which it rebounds p p impact and rebound velocities are measured by the following method a permanent magnet integrated into the impact body passes through a coil and induces an electric voltage during its travels back and forth the voltages are proportiona