The Rockwell Hardness Tester follows a specific procedure to ensure accurate and reliable results. Here's a detailed breakdown of the steps involved:

l Surface Preparation: Like most hardness testing methods, proper surface preparation is essential for accurate results. The test area on the material should be clean, flat, and free from any defects or imperfections. Depending on the material and testing standards, this might involve cleaning, grinding, or polishing the surface.

l Minor Load Application: The testing process begins with applying a small preliminary load, typically around 10 kgf (kilogram-force), to the material surface using the indenter. This minor load establishes a reference point for the subsequent measurement. The indenter itself can be a steel ball or a diamond cone, depending on the chosen Rockwell scale.

l Major Load Application: Once the minor load is established, the main test load is applied.  The specific load value depends on the chosen Rockwell scale. Rockwell testing utilizes different scales (A, B, C, etc.) with varying major load ranges (typically from 60kgf to 150kgf).  Choosing the appropriate scale is crucial for accurate results, as using the wrong scale for a particular material's hardness can lead to misleading values.

l Indentation Depth Measurement: The major load is held for a predetermined dwell time (usually around 15 seconds). After this dwell time, the major load is removed, but the minor load remains applied to the indenter. At this point, the tester measures the depth difference between the initial reference point established by the minor load and the final depth of the indentation left by the major load. This depth difference is a key factor in calculating the Rockwell Hardness Number.

l Hardness Number Calculation: Based on the measured depth difference and the specific Rockwell scale used (A, B, C, etc.), a formula is employed to calculate the Rockwell Hardness Number (HR). The Rockwell Hardness Number provides a quantitative value representing the material's resistance to permanent indentation.