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Lifting Magnets - Knowledge Base

Working Principles of Electro Permanent Lifting Magnets

As the name applies, Electro-Permanent Lifting Magnet is hybrid of electro lifting magnet and permanent lifting magnet. But in nature, it is permanent magnet as a holding device, because the magnetic force is generated by its permanent magnets only. Electro-Permanent Lifting Magnet only uses electricity to turn on and turn off its magnet power.

Electro-Permanent Lifting Magnet is composed of magnet materials, steel parts, coils and electronic control device.

There are two magnetic power sources in Electro-Permanent Lifting Magnet. One is a set of high intrinsic coercive force (Hci) magnets and another is a set of low Hci magnets. The low Hci magnets are wrapped in electrical wire coils. Changing the direction of current pulse in the coils can change the direction of its magnetic orientation.

When the two sets of the magnets have same magnetic direction the Electro-Permanent Lifting Magnet has attractive force to ferromagnetic work piece. If the two sets of the magnets have opposite magnetic directions they absorb each other’s energy, so that the Electro-Permanent Lifting Magnet has no lifting capacity.

A computerized control device switches current pulses to the coils which are wound around the low Hci magnets in reverse directions to magnetize them in contrary orientation. This turns on and off the magnetic power of the Electro-Permanent Lifting Magnet.

Advantages of Electro-Permanent Lifting Magnet:

• Electro-Permanent Lifting Magnet uses electricity a few seconds only to turn on and turn off its magnetic lifting power. During the lifting period, it doesn’t use any electricity and keeps its lifting power even in case of mains power failure. The lifting is safer and less energy consumption than electro lifting magnet.
• Electro-Permanent Lifting Magnet can be turned on and off by a pendant control station, or by a wireless remote control at a distance. It could be used in multiple on a lifting beam, or in an automatic process system.
• Electro-Permanent Lifting Magnet can be adjusted to different lifting capacity, so it can lift one piece of thin sheet metal from a stack without clinging to more sheets.

Disadvantages of Electro-Permanent Lifting Magnet:

• The magnetic flux form Electro-Permanent Lifting Magnet penetrates not far away from its poles. It is very sensitive to the air gap between the magnet and the load to be lifted. The lifting capacity decreases dramatically as the air gap increases. Therefore, the Electro-Permanent Lifting Magnet should not be good for some loads which have uneven or rough surface.
• Electro-Permanent Lifting Magnet could be expensive.