How Does It Work?
A spring in the probe projects the tungsten carbide ball tipped indenter at the test piece. Impact velocity is measured immediately prior to impact and then on rebound. The quotient is computed and displayed as the Leeb Hardness Value. On hard materials, the rebound velocity will be higher than that from softer materials, which will absorb more of the impact energy.
For a correct and repeatable measurement certain conditions must be met:
- The material must be smooth and free of paint, rust, oxide, etc...
- The grain size of the test part must be small in relation to the indentation size.
- The material cannot move or be deflected by the impact of the indenter.
- Correction factor must be applied for the material's elastic modulus.
- Correction for the effect of gravity must also be made.