remagnetising

Remagnetising is the process of restoring or increasing the magnetic field strength of a permanent magnet. Over time and due to various factors such as exposure to heat, shock, or opposing magnetic fields, permanent magnets can lose some or all of their magnetism. Remagnetising involves exposing the weakened magnet to a stronger magnetic field, typically generated by a powerful electromagnet.

The magnet is placed within or very close to the field of the electromagnet. The direction of the applied field is crucial; it must align with the original magnetic orientation of the magnet being remagnetised. If the original polarity is not known or if a complete reversal is desired, the magnet can be placed in a coil and subjected to a strong magnetic field that is then slowly reduced to zero, or reversed and then reduced. This process realigns the magnetic domains within the material, thereby restoring its magnetic properties.

The effectiveness of remagnetising depends on the type of magnetic material. Hard magnetic materials, like those used in permanent magnets, are designed to retain their magnetism once magnetised and are generally amenable to remagnetising. Softer magnetic materials, which are easily magnetised but also easily demagnetised, are less commonly remagnetised in this manner as their magnetic properties are more transient. Equipment used for remagnetising typically includes coils through which a controlled electric current flows to generate the required magnetic field.