Hardness Tester DHT-200
PLUS
3
3. Pre-treatment of work piece
To get the accurate measuring results, pre-treatment of work piece is
required.
3.1 Work piece surface
Temperature of work piece should be less than 80
；
The surface roughness requirements are listed in table 3.1.1
Table: 3.1.1
Impact Device
Work piece of surface roughness
D, DC, D
＋
15, DL
2um
G
7um
C
0.4um
The small support ring or non-conventional support rings are required for
work piece with curved surface radius less than 30mm, for details please refer
to appendix 4.
3.2 Weight of work piece
No support is required for work piece weight more than 5kg.
Work piece with weight of 2-5kg and also heavier work piece with
protruding parts or thin walls should be placed on a solid support. In such a
manner, they do not move or flex during testing.
Work piece less than 2 kg should be rigidly coupled with a non-yielding
support such as a heavy base plate.
Table 3.2.1 Work piece weight and thickness
Impact Device
Weight (KG)
Minimum thickness
of work piece (mm)
Need
coupled
Need
support
No
need
D\DC\DL\D+15
0.1-2
2-5
> 5
3
G
0.5-5
5-15
>15
10
C
0.2-0. 5
0.5-1.5
>1.5
1
3.3 Work piece surface hardened layer
If the work piece surface hardened layer is too thin, the impact force of
short duration will go through the layer and make the L-value incorrect. The
proper depth surface hardened layer is listed below:
