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Aswitchable magnet (commonly used as amagnetic base) is a magneticfixture that uses one or more permanent magnets in a configuration that allows the external field to be turned on or off. They are used in many applications includingoptics,metalworking,lifting, and robotics, to attach items to metal surfaces in a secure but temporary way.[1][2]
A switchable magnetic device usually consists of a magnetic circuit with permanent magnets. By moving some parts of this circuit, the magnetic flux can be directed within the device (off position) or externally (on position).[3]
One type of switchable magnet is made from two blocks ofiron, with a round cavity bored through the center.[1] The halves are joined together with a non-ferrous material such asbrass oraluminium. A roundpermanent magnet is inserted into the bored hole and a handle is attached to allow rotation of the magnet. This act of rotation changes the orientation of themagnetic field.[4]
In theoff position, the poles are oriented towards the non-ferrous core. The iron blocks act askeepers by bridging between both poles.
In theon position, the poles are each in one iron half, which then acts as an extension. The field is effectively passing across an air gap (at the base and top). If this gap is bridged with a piece of iron, it becomes part of themagnetic circuit and will be fixed to the structure.
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