Magnetic Yoke is a hand held devices that induces a magnetic field between two poles. Common applications for the magnetic yoke are for outdoor use, remote locations and weld inspection. For proper inspection the yoke needs to be rotated 90 degrees for every inspection area to detect horizontal and vertical discontinuities. These systems used dry magnetic powders, wet powders, or aerosol cans.
Magnetic particle inspection (MPI) is a non-destructive testing (NDT) process for detecting surface and subsurface discontinuities in ferrous materials. The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. Direct magnetization occurs when the electrical current is passed through the test object and a magnetic field is formed in the material. Indirect magnetization occurs when no electrical current is passed through the test object, but a magnetic field is applied from an outside source (magnetic yoke). The magnetic lines of force are perpendicular to the direction of the electrical current which may be either alternating current (AC) or some form of direct current (DC) (rectified AC).
For a complete list of features and accessories, please check all our Magnetic Yokes models below. If you are having difficulties finding the product you need, feel free to contact us and a product specialist will be happy to assist you finding a quality Magnetic Yoke that fits at a great price!
Yokes are the power tools for Magnetic Particle Inspection. These handheld electromagnets create a magnetic field in a Steel (Ferrous) work piece.
Particle Mobility, are the forces that effect the movement of Magnetic Particles on the surface of the work piece. The higher the Particle Mobility the faster, and more reliable, the particle will congregate to a defect or a change in surface profile. Let us outline the fields produced by Yokes to help you understand the right Yoke for you.
| AC | AC/DC | Safety & Premium | Battery Powered | Permanent Magnet Yokes | Specialty |
| Models: | Models | Models | Models | Models | Models |
| Western Instruments WE-3 Standard AC Yoke | Western Instruments WE-7 Compact AC/DC Magnetic Yoke | Western Instruments WC-6 Compact AC Magnetic Yoke | Western Instruments WC-8 Compact 12 Volt Pulsed DC Magnetic Yoke | Western Instruments WM-Series Permanent Magnet Yokes | Western Instruments WC-6x2 High Lift AC Magnetic Yoke |
| Western Instruments WE-3HD Heavy Duty Standard AC Magnetic Yoke | Western Instruments WC-9 Cordless Magnetic Yoke | Western Instruments WC-9 Cordless Magnetic Yoke | Western Instruments W-PT Pull Test Bars | Western Instruments W-6CS AC Cavity Yoke | |
| Western Instruments WE-3LT Light Weight AC Magnetic Yoke | Western Instruments WC-42 European AC Safety Yoke | Western Instruments W-PPS Portable Inverter Power Supply | Western Instruments WC-6UW Compact Underwater Yoke | ||
| Western Instruments WC-6 Compact AC Magnetic Yoke | Western Instruments WC-42 European AC Safety Yoke | ||||
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| These fields provide the greatest particle mobility as the frequency of the power simply causes the Particle to vibrate. The polarity at each pole (leg) alternates from positive to negative at the same frequency as the electrical input current of 50 to 60 Hertz (pulses per second) | The fields provide is identical to those outlined above. The DC Portion from Yokes is a Phase Controlled pulse or rectified AC. The inductance of the Yoke’s Coil and Iron Core is enough that the Field induced into the material is Straight DC, with a slight ‘ripple’ due to the AC input frequency of 50 or 60 Hertz. |
The AC Yokes Safety & Premium provide the most convenient safety to operators. The Cordless Yoke provides the best mobility, for an Inspector or the NDT Technician. | These yokes take the 12 Volts DC from the Battery and Chops the current, simply turning the field on and off at 125Hz. This Chopping of the electrical supply lowers the effective draw on the battery, thus extending the useful life of a charge. As the chopped current keeps re-energizing the coil, the flat level of the DC curve is interrupted creating a ripple effect that induces some particle mobility | These yokes simply induce a magnetic field into the work piece, almost the equivalent of a full wave DC field. As a result there is no change in the strength or polarity (frequency) of the field, thus there is very low Particle Mobility | When our regular Yoke is not enough we have created Specialty Yokes with the toughest jobs in mind. We have developed these Yokes to fill the needs of working with unusual and tight work piece configurations. |
To summarize the Particle Mobility of Magnetic Fields induced by Yokes, our AC Yokes provide the best Particle Mobility, with AC/DC Yokes being second best, next is the Battery Operated Yokes with Permanent Magnet Yokes last. However, let us be mindful that a DC Field will highlight both surface and subsurface defects while AC only highlights surface indications. So in conclusion, a DC Field with a more pronounced collapse, between pulses, would be beneficial for increased Particle Mobility. We have a Yoke to address various needs of any operator.
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