NewSonic SonoDur2 - Page 9

NewSonic SonoDur2 Issue 04 09/2016 Page 9
The table below shows a few examples of the more significant penetration depth (in “µm”):
Hardness
HV10
HV5
HV1
HV0.3
HV0.1
800 HV
22
15
7
4
2
600 HV
25
18
9
5
2,5
300 HV
36
25
11
6
4
Table 2-1
In general, the nature of the component surface in the range of low-load hardness testing, are of
particular importance. High dispersion of measured values can be an indication of excessive surface
roughness. In this case, reworking of the surface with suitable abrasives as well as a re-measurement
may be recommended.
Some other influencing factors are summarized in the following:
 Minimum layer thickness: 10 x d (no noticeable influence by the base material after
adjustment)
 Minimum material thickness without coupling: > 3 mm (component resonances can falsify
measurement values)
 Minimum mass without coupling: > 0.3 kg (component resonances can falsify measurement
values or may make it impossible to perform a measurement)
 Minimum distance from the component edge of the element = 3 x Ld, between the
indentations = 6 x Ld
 The surface roughness should be much less as the penetration depth (< 1/5 x d)
In the latest issue of the German standard DIN 50159-1,2-2015 examples for the required surface
roughness Ra for different test loads and as well for the grit size for the manual grinding work are
given, see tables below:
Testload [N]
10
50
98
Ra [µm]
0,5
0,8
1,0
Ra [µm] ASTM
5
10
15
Tabelle 2-2: Guidelines for the maximum surface roughness according to EN ISO 6507 (Vickers) and
information given in the standard ASTM A 1038
Sand paper grit size
120
180
240
Ra [µm]
1,2
1,0
0,6
Tabelle 2-3: Surface roughness after manual grinding using sand paper with various grit size (FEPA-
Standard, „Federation of the European Producers of Abrasives“).
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