A description of the manufacturing process, with definitions of “hard” and “soft” in scientific terms.
To produce ordinary magnets, factories place pieces of Iron, Cobalt and Nickel in the field of a powerful electromagnet.*
After a slight delay, known as hysteresis, the torque exerted by the electromagnetic field causes the domains inside the magnet-to-be-rotate, lining up with the north/south lines of the electromagnetic field. Those which are already pointing in the right direction expand, while the domains around them shrink. To accommodate this process, the domain walls rapidly change shape, sometimes vanishing entirely. When the process is completed, the metal pieces will have turned into magnets.
*The more powerful electromagnets are in turn made by placing a piece of Iron, Cobalt or Nickel inside a coil of wire and applying an electric current. This has the same effect as simply placing it in the field of an existing electromagnet, but the end result is a lot more powerful. Another difference is that an electromagnet can be magnetised and demagnetised at the flick of a switch (in a working electrical circuit).
Sometimes magnets may also be created using lodestone, a magnetic mineral found on the surface of the earth. When extracted, this can also be used as magnet material, or be used to magnetise the three metals: Iron, Cobalt and Nickel. Different magnets hold their magnetism for different lengths of time. Stronger, more permanent magnets are known as “hard” while the weaker magnets which lose their magnetism over time are known as “soft”.
- various magnet company sites