KERN & SOHN HMR - Manual (Page 3)

Sauter GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [email protected] Tel: +49-[0]7433- 9933-199
Fax: +49-[0]7433-9933-149
Internet: www.sauter.eu
Instruction Manual
HMR
HMR-BA-e-1212 3
3. Guide Tube
4. Coil unit
5. Connection cable
6. Impact body
7. Support ring
2.1.4 Different types of Impact Devices
2.2 Leeb Hardness Testing Principle
The basic testing principle is to use an impact body of a
certain weight which impacts against the testing surface
under certain test force. The impact velocity and the
rebound velocity of the impact body are measured
respectively when the spherical test tip is located 1mm
above the surface being tested.
The calculation formula is as follows:
HL= 1000 x VB/VA
Where HL= Leeb Hardness Value
VB= Rebounding velocity of the impact body
VA= Impact velocity of the impact body
3. Technical Specifications
 Error and repeatability of the displayed value,
see Table 3-1:
N
o
.
Typ
e of
im
pact
devi
ce Hardness value
of
Leeb
standard
hardness block
Error of
displayed
value
Repeata
bility
1 D
760±30HLD
530±40HLD ±6 HLD
±10 HLD 6 HLD
10 HLD
2 DC
760±30HLDC
530±40HLDC ±6 HLDC
±10 HLDC 6 HLD
10 HLD
3 DL
878±30HLDL
736±40HLDL
±12 HLDL 12 HLDL
4
D+
15 766±30HLD+15
544±40HLD+15 ±12
HLD+15 12
HLD+15
5 G
590±40HLG
500±40HLG
±12 HLG 12 HLG
6 E
725±30HLE
508±40HLE
±12 HLE 12 HLE
7 C
822±30HLC
590±40HLC
±12 HLC 12 HLC

Measuring range: HLD: (170 ~ 960) HLD
 Measuring direction: 0 ~ 360°

Hardness Scale: HL, HB, HRB, HRC, HRA,
HV, HS

Display: dot matrix LCD,128 x 64 dots

Data memory: max. 500 groups
 Power supply: 3V, (2AA size Alkaline batteries)

Continuous working period: about 50 hours
(with backlight off)

Communication interface: USB1.1
4. Preparation & Testing
4.1 Preparation and Inspection before Testing
4.1.1 Preparation of Sample Surface
Preparation of the sample surface should conform to the
relative requirements in APPENDIX Table 3.

During the preparation of the sample surface,
any heating or cold processing on this surface
should be avoided.

Too big roughness of the surface being
measured could cause errors. The surface of the
sample should show metallic luster, be smooth
and polished, without any stains of oil etc.
 Support of the sample is not necessary for
heavy objects. Medium-weight samples have to
be placed onto a smooth and stable plane. It
must be placed in absolute equability and
without any wobble.

Curved surface: The best testing surface, of
course, is flat. When the curvature radius R of
the surface to be tested is smaller than 30 mm
(D, DC, D+15, C, E and DL type of impact
device) and smaller than 50 mm (G type of
impact device), the small support rings should
be chosen.

The sample should have enough thickness, the
minimum thickness of it should conform to
Table 3.
*For a sample with a hardened layer on its surface,
the depth of the hardened layer should also conform
to Table 3.

Coupling: Light-weight samples must be firmly
coupled with a heavy base plate. Both coupled
surfaces have to be flat and smooth; there may
not rest any redundant coupling agent. The
impact direction must be vertical to the coupled