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Leeb Measuring Method – (For MET-UD only)
History
The Leeb measuring method was first brought into measurement technology in 1978. It is defined as the quotient
of an impact body’s rebound velocity over its impact velocity, multiplied by 1000. Harder materials produce a
higher rebound velocity than softer materials. For a specific group of material (e.g. steel, aluminum. etc.). Leeb
hardness value represents a direct relationship to its hardness properties. For ordinary metal, conversion curves of
hardness HL versus other standard static hardness (HB, HV, HRC, etc.) are available, enabling you to convert HL
into other hardness values.
Leeb Hardness Test (definition)
An impact body with a spherical test tip made of tungsten carbide is propelled against the sample surface by a
spring force and then rebounds back. At a distance of 1mm from the sample surface, the impact and rebound
velocity of the impact body are measured by the following method: A permanent magnet embedded in the impact
body, when passing through the coil in its coil holder, induces in the coil an electric voltage proportional to the
velocities of the magnet. Leeb hardness is expressed by the following formula:
A Leeb’s Hardness
Tester
measures the hardness of sample material in terms of Hardness Leeb (HL),
which can be converted into other Hardness units (Rockwell B and C, Vicker and Brinell).
HL = 1000 x (V
B
/V
A
)
Where: HL is Leeb Hardness
V
B
is the rebound velocity of the impact body
V
A
is the impact velocity of the impact body
The voltage characteristic of output signal, when the impact body passes through the induction coil is
illustrated in the following figure: