Electro magnets have been used  in industrial lifting applications for over  100 years and their  working principle as well as their two main generic components are well known, these being  a ferrous core fitted with pole shoes (polarities) at its extremity and  an electro conductor winding (typically made of aluminum or copper) surrounding part of the  core. The passage of direct current through the winding results in the magnet being energized.

The lifting force of an electro magnet  is determined by  three factors which are:

  • The size (and geometry) of the ferrous core (the larger, the stronger)
  • The quantity of turns that constitute  the winding (the more, the stronger)
  • The quantity of direct current (Amps, Idc) passing through the winding  (the more, the stronger)

Once an electro magnet is designed and built,  the first two elements (size and turns) are set while the third one (current) can vary based on direct voltage (Vdc) setting and winding temperature that impacts the electrical resistance (R) of the winding conductor (Vdc= R x Idc). Electro magnets generate heat (Joule effect) when energized and the hotter the magnet winding, the more the current decreases.
The four elements that impact the internal temperature of an electro magnets are:

  • Temperature of material to be lifted (in case of  a hot application)
  • Duty cycle
  • Current density  of the winding conductor
  • Type of winding conductor.

The first two elements (material temperature and duty cycle)  are specific to every application and situation while current density and the type of magnet winding  conductor are decided by magnet designer.

In order to optimize heat dissipation, magnet force and magnet life time, the SGM electro magnets are designed with very conservative electrical density for their winding and, as a standard,  their  windings  are of  anodized aluminum strip.  

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  • SGM Magnetics S.p.a.
  • Address: via Leno 2/D - I-25025 Manerbio (BS) - Italy
  • Phone: +39 030 9938400
  • Fax: +39 030 9938404
  • Email: info@sgmmagnetics.com
  • P.Iva: 00561630989 | C.F.: 00436040174
  • Capitale Sociale : Euro 750.000 | Reg. Soc.: Tribunale BS n. 9213
  • C.C.I.A.A.: Brescia 182441 | Meccanografico: BS 029733
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