Tutorial On Leeb Rebound Hardness Testing; Test Principle; Sample Preparations; Test Conditions - Proceq Equotip 3 Operating Instructions Manual

2. Tutorial on Leeb rebound hardness testing

2.1. Test principle

During measurement with Equotip 3 impact devices (D, DL, DC, C, G, S, E), an impact body
with a ball indenter is launched by spring energy against the sample to be measured, and then
rebounds. Before and after the impact, a permanent magnet inside the impact body passes
through a coil in which a voltage signal V is induced by the forwards and backwards move-
ment. This induction signal behaves proportionally to the velocities. The ratio of the rebound
velocity v to the impact velocity v
r
ness). HL is a direct measure of the hardness.

2.2. Sample preparations

Keep the sample free of vibrations during the test. Light and thin parts must be specially fas-
tened (see section 2.6. "Testing light samples"). Ensure that the surface of the work piece is
clean, smooth and dry. If required, use appropriate cleaning agents for cleaning, such as ac-
etone or isopropanol (no water!).

2.3. Test conditions

Impact device type
C
D, DC, DL, S, E
G
Impact device type
C
D, DC, DL, S, E
G
Impact device type
C
D, DC, DL, S, E
G
Impact device type
G
D, DC
DL
C
S
E
Impact device type
C
D, DC, DL, S, E
G
© 2012 by Proceq SA
multiplied by 1000 yields the hardness value HL (Leeb hard-
i
Sample of
compact shape
1.5 kg (3.3 lbs)
5 kg (11 lbs)
15 kg (33 lbs)
Minimum sample thickness
Uncoupled
10 mm (2/5 in)
25 mm (1 in)
70 mm (2 in)
Roughness class
ISO
N5
N7
N9
Maximum sample hardness
in HL in HRC
750 HLG N/A
890 HLD ~ 68 HRC
950 HLDL ~ 68 HRC
960 HLC ~ 70 HRC
890 HLS ~ 70 HRC
855 HLE ~ 72 HRC
Between indentations
2 mm (1/12 in)
3 mm (1/8 in)
4 mm (1/6 in)
Minimum sample weight
Sample resting
on solid base
0.5 kg (1.1 lbs)
2 kg (4.5 lbs)
5 kg (11 lbs)
Coupled
1 mm (1/25 in)
3 mm (1/8 in)
10 mm (2/5 in)
Sample surface condition
Maximum roughness
depth Rt
2.5 µm (100 µin)
10.0 µm (400 µin)
30.0 µm (1'200 µin)
in HV
~ 675 HV
~ 955 HV
~ 955 HV
~ 1010 HV
~ 965 HV
~ 1200 HV
Minimum space
Between indentation and sample edge
4 mm (1/6 in)
5 mm (1/5 in)
8 mm (1/3 in)
Coupled to
solid base
0.02 kg (0.045 lbs)
0.1 kg (0.25 lbs)
0.5 kg (1.1 lbs)
Top layer
thickness
0.2 mm (8 µin)
0.8 mm (32 µin)
N/A
Average rough-
ness depth Ra
0.4 µm (16 µin)
2 µm (80 µin)
7.0 µm (275 µin)
in HB
~ 645 HB
N/A
N/A
N/A
N/A
N/A
5