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Examples
of Visible Dry
Magnetic Particle Indications
Eddy
Current:
A
current induced in a conductor situated in a changing magnetic
field or moving in a fixed one.
Ultrasonic:
The
study and use of pressure waves that have a frequency in excess
of 20,000 Hz and therefore inaudible to the human ear.
One of the advantages that a magnetic particle inspection has
over some of the other nondestructive evaluation methods is that
flaw indications generally resemble the actual flaw. This is not
the case with NDT methods such as ultrasonic
and eddy
current inspection, where an electronic signal must be interpreted.
When magnetic particle inspection is used, cracks on the surface
of the part appear as sharp lines that follow the path of the
crack. Flaws that exist below the surface of the part are less
defined and more difficult to detect. Below are some examples
of magnetic particle indications produced using dry particles.
Indication of a crack in a saw blade
Indication of cracks in a weldment
.jpg)
Indication
of cracks originating at a fastener hole
Before
and after inspection pictures of cracks emanating from a hole
Mag_Indication).jpg)
Indication
of cracks running between attachment holes in a hinge
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