Manual
4
1
Introduction
Thank you for purchasing a PCE-2500 hardness tester from PCE Instruments.
1.1
Forewords
1.1.1
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.
1.1.2
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:
1000
*
Vi
Vr
HL
Where: HL is Leeb Hardness
Vr is the rebound velocity of the impact body
Vi 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:
Voltage characteristic of output signal
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, Brinell and Shore D).
