Magnetization Yoke:
There are two basic types of yokes that are commonly used for magnetizing purposes:
Both yokes are handheld and therefore it easy to use. we already discuss these yokes in our previous tutorials, follow the above-given link to read more...
Yoke Calibration:
Yoke Equipment could be Alternating current (AC) or Direct current (DC). Ac Yoke shall lift weight of al least 10 lbs (4.5 kg) at the maximum pole spacing that will be used. and for the DC yoke shall lift weight of at least 40 lbs (18 kg) at the maximum pole spacing that will be used. When yoke lifting capacity is tested, the yoke shall be able to lift the weight slightly above the ground (4" to 6") with maximum leg spacing that will be used.
Longitudinal Magnetization:
Electromagnets yoke is basically made by wrapping an electrical coil around a piece of soft ferromagnetic steel. The circular current pass through the coil and as per Right-hand rule, its produce Longitudinal Magnetization. A Longitudinal magnetic field has magnetic lines of force that run parallel to the long axis of the part.
Any discontinuity that is perpendicular to the magnetic lines of force will show, if the discontinuity is parallel to the line of magnetic line of force, there will be no leakage in magnetic flux and therefore no indication observed.
To resolve this issue, each area needs to be examined twice. the second examination needs to be perpendicular to the first examination so discontinuities in any direction could detected.
Right-hand rule:
Right-Hand rule says, if the person grasps a conductor in his right hand with the thumb pointing in the direction of the current, the fingers will point in the direction of the Magnetic field.
In This case, if the Fingers point to the direction of current, the Thumb will point in the direction of Magnetic Field.
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When an electric current flow in a straight line from one contact point to the other, The magnetic lines of force are in a circular direction. & When the current flow is through a coil around the test piece, the magnetic lines of force are longitudinal through the test piece.
Here are some example to know, how we can use Magnetization yoke to make better Magnetic Particle Inspection.
