8
Determining the Correct Force: To determine the correct for Brinell testing the indentation
diamond should be in the range of 0.25 to 0.6 times the ball diameter (see chart below). The
maximum accuracy of the measurement is achieved when the diameter of the indent is 0.37
times the diameter of the ball indenter.
Indenter Ball
diameter
(mm)
Min. size of
indent =
(0.25xD) mm
Max. size of
indent =
(0.6xD) mm
Most accurate
size of indent =
(0.37xD) mm
2.5
0.63
1.50
0.93
5
1.25
3.00
1.85
10
2.50
6.00
3.70
The following table also help determine the correct Brinell hardness ranges, based on the
materials being tested:
Material
Brinell hardness
F/D
2
Steel,
nickel alloy, titanium alloy
—
30
Cast iron
＜
140
10
≥140
30
Copper & copper alloy
＜
35
5
35~130
10
＞
130
30
Light metal & its alloy
35
2.5
35~80
5,10
＞
80
10
F—test force (kg) ; D—ball diameter (mm)
Repetition and tolerance of displayed value for the hardness tester:
Standard hardness test
block
Tolerance of displayed
value%
Repetition of displayed
value%
≤125
±3
3
125<HBW≤225
±2.5
2.5
＞
225
±2
2
