Ways of Demagnetizing

Written by paul cartmell
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There are many ways of demagnetising magnets and magnetic equipment with uses in many industries. Some are more technical than others which, simply require brute force.


Materials become demagnetised when magnetic molecules within a substance are randomised, causing general disorder within the magnetic material. For magnetism to occur, the magnetic molecules or unit magnets are aligned in one direction, creating a uniform force of molecules pulling in the same direction. If a magnet is broken, each part of the broken magnet will create the two poles of a magnet called north and south. Individually each broken piece will become a magnet.


Heating a piece of magnetised metal in a flame will cause demagnetisation by destroying the long-range order of molecules within the magnet. By heating a magnet, each molecule is infused with energy. This forces it to move, pushing each molecule out of order within the magnet and leaving the piece of metal with very little or no magnetisation.


When a magnet is hammered or dropped, the vibrations caused by the impact on the magnet randomise the magnetic molecules within the magnet, forcing them out of order and destroying the long-range order of the unit magnet.

Alternating Current (AC) Field

Using an AC current produces a magnetic field which can be moved and reduced to demagnetise materials. The field created by the AC current drags the magnetic molecules of the magnet in different directions. When the AC current is altered or reduced, the molecules within the magnet do not all return to previous positions, causing randomisation of the molecules and reducing the force of the magnet.

Magnetizer/Demagnetizer Tools

Magnetizer/Demagnetizer tools (VTMDs) are used to magnetise and demagnetise steel tools, such as the tips of screwdrivers, in seconds. The tool to be magnetised or demagnetised is inserted into the magnetizer hole and shaken from side to side, repeating until the entire tool is magnetised or demagnetised.

Demagnetising Tape Heads

Recording engineers demagnetise tapes and tape machines before recording sessions in a recording studio using magnetic recorders. You should remember to remove tapes and turn off the power to the tape recorder before turning on the power to the demagnetiser. Once the power is turned on to the demagnetiser, bring the tip of the demagnetiser to the tape head and slide it across the tape head five times. When the demagnetisation is complete, slowly pull the demagnetiser away from the tape recorder and unplug the demagnetiser before using the tape recorder.

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