The Rockwell hardness testing is a procedure for calculating the hardness of metals and certain plastic materials. The simplicity of the test is its strength, and the Rockwell hardness scale is relied upon to characterise the metals’ hardness for items such as steel, lead, aluminium, copper, zinc, alloys, iron, and titanium, and specific polymer plastics.
The test was first devised by Stanley Rockwell, and it was first conducted in 1919. A materials hardness rating, as assessed by the Rockwell scale, refers to the material’s opposition to penetration. The test is designed to measure material hardness via a basic procedure; by pressuring an indenter into the materials’ surface using a specific weight, and then measuring how much the indenter was able to pierce the material. The indenter can be either a hardened steel ball or a conical shaped diamond.
Rockwell hardness testing is performed as follows: Using a pre-defined minor, or initial, load, the indenter is pressed into the sample material that is being tested. A heavier load is then enforced and held in position for a specific period. After this timeframe has expired, the indenter is reverted back to the original minor load. The Rockwell hardness result is determined by measuring the depth of the permanent indentation that was caused by the indenter. Essentially the measurement is the difference in the indenter position, before and after the application of the heavier load compared to the minor or initial load.