Manufacture
The first magnets used were common cylindrical or solid rectangular magnets. Later, a flexible magnet was developed, composed of a high-coercivity ferromagnetic compound (usually ferric oxide) mixed with a plastic binder. This is extruded as a sheet and passes on a conveyor belt over a line of powerful cylindrical permanent magnets. These magnets are arranged in a stack with alternating magnetic poles facing up (N, S, N, S,...) on a freely rotating shaft. This impresses the plastic sheet with the magnetic poles in an alternating line format. No electromagnetism is used to generate the magnets. The pole-pole distance is on the order of 5mm, but varies with manufacturer. A refrigerator magnet will be demagnetised by passing it over a stronger magnet. Decorative elements are then attached to the magnets with adhesive.
Read more about this topic: Refrigerator Magnet
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