9
10
required indentation error and repeatability
scale
HRA
HRB
HRC
hardness range
20~75HRA
75~88HRA
20~45HRB
45~80HRB
80~100HRB
20~70HRC
indentation error
repeatability
±
2HRA
±
1.5HRA
±
4HRB
±
3HRB
±
2HRB
±
1.5HRC
≤
1.5HRA
≤
1.5HRB
≤
1.5HRC
4.6 If something unusual happens to the hardness tester, do not
disassemble or adjust any structure, please contact us to solve
this problem.
6
10
13
16
19
22
25
32
38
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
3.0
2.5
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0.5
3.0
2.5
2.0
2.0
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0
3.0
2.5
2.0
2.0
1.5
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0
2.5
2.5
2.0
1.5
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0
0
2.0
2.0
1.5
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0.5
0
0
1.5
1.5
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0.5
0
0
0
1.5
1.0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0.5
0
0
0
0
1.0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0
0
0
0
0
0
0
1.0
1.0
0.5
0.5
0.5
0.5
0.5
0
0
0
0
0
0
0
0
Hardness
value (HRC)
(HRA)
Diameter of cylindrical surface(mm)
Correction
of
Rockwell A/C scale
Attention:
If the diameter is not included above, interpolation
method is proposed.
For example:
If the measuring surface is an 8mm cylindrical surface, the
correction can be worked out when the measuring hardness
value is 60HRC.
It is easy to find when the hardness value is 60HRC, the
correction of 6mm and 10mm is 1.5 and 1.0, so 1.25 could be
recognized as the correction pf 8mm cylindrical surface.
g. The minimum of the test sample thickness should be more
than ten times of the depth of indentation. After test, the back
of the test material should has no visible deformation traces.
And the relationship of the test sample minimum thickness
and hardness value could be found as per below form:
Maintenance
4.1 Keep clean and away from dust, corrosion and rust in daily
work or after using the hardness tester.
4.2 Be careful when install or take off the indenter, and grease is
also needed if not used for a long time, keep it well.
4.3 The stage and the hardness standard block should be clean,
flat, or any no scratch, paint some antirust grease before store.
4.4 The lifting screw should be lubricated regularly. The detail
operation: take off the stage and the case of screw, paint some
antirust grease on the screw, then rotate the lifting handwheel to
lift the screw up and down, so the grease could be uniform. At this
moment, you can put the case and stage back.
4.5 Check the indentation error and repeatability with hardness
standard block regularly. If the value out of range, need to check
if any wrong with the hardness tester.
Attention: The surface with words marked on the hardness
standard block is the measuring surface.
HRA
HRB
HRC
Hardness value
Mini-thickness
20 30 40 50 60 70 80 90
20 30 40 50 60 70
20 30 40 50 60 70 80 90
1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2
1.6 1.4 1.2 1.0 0.8 0.6
100
3.3 3.0 2.7 2.4 2.1 1.8 1.5 1.2 0.9
Remark: the unit of mini-thickness is mm.
Hardness value
Mini-thickness
Hardness value
Mini-thickness
