A Rockwell hardness tester is one of four common types of hardness testing (with Brinell, Vickers, and Leeb). It is most commonly used for metallic material.
In order to successfully test metallic hardness with a Rockwell tester, the tester will feature either a diamond cone or tungsten carbide metallic ball to create the impact in the test metal. A minor (lighter) load is forced upon the material, followed by a major (heavy) load. Then, the machine calculates the difference in millimeters between the two indentations and produces a hardness reading. Diamonds and tungsten carbide are two of the hardest materials on Earth, diamonds being used for the absolute hardest of materials, while tungsten carbide is use for slightly softer materials. One of the two will successfully indent any material you choose.
In order to interpret the reading from a Rockwell hardness tester, it is important to understand the Rockwell scales. The values a Rockwell tester outputs are a combination of a hardness number followed by HR and a scale symbol. For example, a reading of HRC 63 indicates a hardness level of 63 on the Rockwell ‘C’ scale. The higher the value, the harder the material.
Rockwell test methods are specified in three standards. One is entitled the ASTM E 18 metals. Auditors will use these standards to assess QC on your equipment. To ensure compliance, make sure your Rockwell hardness tester is calibrated with Class A indenters that are traceable to the National Standards. All manufacturers now must standardize their hardness readings in compliance with these requirements. Be sure you are verified at level E 18-03 or later to conform to test compliance rules.
You may also be interested in portable hardness testers. These provide ease of use and cost savings while remaining faithful to the Rockwell method. Such tester may be useful in test the hardness of a metallic ring, manufacturing/milling equipment, lathes, or other platforms.
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