HardyTest D400
2. Technical Specification
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2.1 Principal of Measurement
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The HardyTest D400 is a instrument for hardness testing which works on the basis of the HL/
HLD principal. This method was first introduced in 1978 by Ing. D. Leeb. The idea is that an
impactor falls on another objects and rebounds. The harder the object is the greater the
rebound velocity is. Therefore the value HLD is calculated by the quotient of the rebound
velocity and the impact velocity multiplied with 1000.
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If we consider a certain set of materials like steel, aluminum etc., the HLD value with which
the above-mentioned pieces were measured represents a direct hardness value and, as
such, can be used for a further comparison with other hardness values (Brinell, Vickers,
Rockwell, Shore, etc.).
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Note:
The HardyTest D400 only works with hydraulic impactors of the type D.
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