Operation

• Set the indicator on the hardness tester to the reading position. Begin loading the hardness tester. The indenter (a penetrating cone of metal) is positioned to make contact with the test material at a 120-degree angle. Preset the level of pressure to be applied to the test material (known as the preload). Release the indenter so that it makes impact with the test material. Record the depth of the indentation for comparing with the next test. For the next test, apply pressure at a different area on the surface of the test material. Maintain this pressure for a preset time. It is referred to as dwell time and is usually several seconds. The result is an indentation or mark defacing the test material to some degree. Compare the difference between the two indentations. The difference is the measured hardness of the test material.
  
  

Total Force

• Total force is the addition of more force applied to the preload force on the test material. This extra force is held for a time before returning the force level back to the preload setting. The preload setting is applied for a fixed time. To get the reading for the total force (some authorities refer to it as the "Major Load"), remove the indenter, and then compare the difference between the depth of the indentation created by the additional force and the depth created by the preload setting.