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Lifting Magnets - Knowledge Base

Working Principles of Permanent Lifting Magnets

Lifting Magnet NL-660B(2)

Permanent lifting magnets are composed of magnet materials and steel parts which build a path through which the magnetic flux goes from the magnet materials to ferromagnetic load to be lifted.

NL-B series permanent lifting magnets are assembled with high grade Neodymium magnets and mild steel in order to get high magnetic power and compact sizes.

A NL-B permanent lifting magnet has two magnetic sources, one is in the main body and another is in the rotor. When the two magnetic sources are at same magnetic direction the lifting magnet project magnetic flux to a ferromagnetic load underneath its poles. In contrast, when the two magnetic sources are at opposite magnetic direction they absorb each other’s energy and no magnetic flux can go out from the lifting magnet. Meanwhile, the lifting magnet has no attraction to the load.

By turning the handle of the lifting magnet you change the magnetic direction of the magnetic source in the rotor and therefore to attract and release the load.

Permanent lifting magnets have some advantages as follows.

  • Permanent lifting magnets use magnet materials as the magnetic sources and don’t need any external power supply. So that they can be used any place.
  • Permanent lifting magnets are composed of magnet materials and steel parts only, they are durable with little maintenance.
  • Permanent lifting magnets can be simply operated by hand. The operation of permanent lifting magnets are very easy.
  • The costs of the permanent lifting magnets are lowest among all types of lifting magnets.
But, permanent lifting magnets have some disadvantages.
  • The magnetic field from the poles of the permanent lifting magnets are shallow, compared to electro lifting magnets. Consequently the lifting capacity of the permanent lifting magnets decreases significantly as the air gap between the magnet and the load to be lifted increases. Any dust, scraps, paint, and rust contribute the air gap.
  • There are two limitations of the load thickness. First is for the rated lifting capacity, the actual lifting capacity will less than the rated capacity if the load thickness is less than this limitation. The second limitation is for turning the handle. You cannot turn the handle if the load thickness is less than this limitation.
  • The larger the lifting capacity of permanent lifting magnets, the harder the turning of the handle from OFF position to ON position. The maximum capacity of permanent lifting magnets should be 2,000 kgs (4,400 lbs), over which it is hard to turn the handle from OFF to ON. (A few manufacturers make permanent lifting magnets of lifting capacity over 2,000 kgs. However, these big lifting magnets are not easy to turn the handles.)
  • Permanent lifting magnets are operated manually and cannot be controlled from distance. They are not used in an atomization system.
In summary, if your workloads to be lifted are
  • Flat, thick and relatively clean plates, or
  • Regular rounds
(Details please read Instruction Manual)

You could select permanent lifting magnets to use. Otherwise, please consider electro lifting magnets and electro-permanent lifting magnets.