rockwell indentation hardness test. apparatus gnehm om-150 universal hardness tester
TRANSCRIPT
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