Rockwell Indentation Hardness Test

Apparatus

GNEHM OM-150 Universal Hardness Tester

Apparatus Diagram

Set knob to correct load.Rockwell C test - set knob to 150kg

Rotate load lever to vertical position

Steel item prepared for testing

Select correct penetrating element

Rockwell C 120 degree conical diamond indenter

Remove existing element

Insert new element

Rotate capstan clockwise until test piece is pressed against metal stops

Apply preload (Rockwell C is 10kg)

Rotate load lever anticlockwise to horizontal position

Set outer dial Rockwell C gauge to zero

record setting, 300 in this case

Rotate load lever anticlockwise to vertical down position to apply the final load.

An additional 90kg applies a final load of 100kg

Record dial reading124 in this case

Calculate test piece hardness

300-124 = 76i.e.

76 HR C

Hardness value

Rockwell Hardness

Rockwell C Scale