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How do Permanent Lifting Magnets Work?
Posted on Aug 7, 2017
Armstrong Magnetics Inc. offers several options of permanent
lifting magnets for different lifting operations. For thicker flat contact area of load,
we normally recommend our NL-B series industrial magnetic lifters as the most effective and low
price option. So how do they work and how are they made?
- First of all, a powerful permanent magnet material should be selected. It should display high coercivity or resistance to demagnetization. Rare-earth Neodymium magnets are commonly used as the core magnetic source.
- At its ON position, a closed magnetic loop should have magnetic flux flowing from North pole to South pole and concentrating at the magnetic lifter pole faces at the bottom to effectively attract any ferromagnetic material. Contrarily, at its OFF position, the magnetic circuit would be manually disconnected by redirecting the flux away from the pole surfaces.
- Even though the magnetomotive force (MMF) increases with increasing strength of the raw magnet material, the cost of permanent magnets needs to be taken into account when designing lifting magnets.
- A free-rotating second magnet is introduced to switch the magnetic loop from closed to open, and vice versa.
- Residual magnetic force must be kept at minimal at OFF position; in other words, magnetic flux from the inside magnets should be diverted away from the pole faces. You wouldn’t want debris.
- Safety latch should make sure that it is impossible to unlock the rotational handle bar, even when the magnetic lifter encounters impact during a lift job.