Equipment Spotlight: Rockwell Hardness Tester

Hardness is a material’s resistance to indentation. The Rockwell hardness test method measures the permanent depth of an indentation created by a load applied to a material. Different indenters, such as diamond and ball indenters, can be used during this process depending on the test material. The process of hardness testing using the Rockwell method begins with the application of a minor load to the material to allow for a baseline depth of indentation to be measured. Then, a major load is applied to reach the total test load and is held for a specified time. The major load is released, returning the test back to the minor load. Hardness can be calculated during the distance measured between the minor load and major load indentions, or the permanent depth of indentation.

Hardness is not a fundamental physical property but rather a characteristic of a material—the material’s resistance to indentation, deformation, penetration or scratching—determined by one of many different hardness testing methods. The Rockwell method of hardness testing is the most common hardness test due to its reliability, consistency and speed of testing. Hardness testing is minimally non-destructive, and the information gained from hardness testing complements other material tests, such as tensile testing, to provide a complete profile of the material properties of a part or product. Determining a material’s hardness is useful in the selection of materials, for determining differences between materials, and for quality control of existing parts or products. The hardness of a product is vital to know when determining if a part of product has the properties needed for its proposed use.