Holding magnets develop high attraction forces to flat magnetic materials. They are used to pick up or hold magnetic materials ranging from holding of ferromagnetic work pieces during machining or assembly operations through door latching or holdback devices to selector devices in textiles machinery.
There are three physical principles of how they work:
- Electro magnet (EM): the magnetic field is produced by putting current into a coil
- Holding magnet with electrical release (HMER): in this design the flux is generated by a permanent magnet; to turn off the attraction force the coil needs to be energised so that it produces a flux in the opposite direction which cancels the field of the permanent magnet.
- Holding magnet (SMPD): in this design the flux is generated by a permanent magnet; it is a permanent field and there is no option to switch it off.