Failsafe operation is the unique advantage of permanent lifting magnets. They are immune to power failures.
Permanent lifting magnets provide a quick and efficient way to lift, lower and vertically or horizontally transport sheet, flat and round steel, such as plates, forgings and die castings. Since they do not require electricity to operate, they have a built in failsafe feature that eliminates the work safety hazards caused by power failures.
Overview of Permanent Lifting Magnets
Permanent magnet lifters are made from two types of magnets: Rare Earth and Ceramic. Lifting magnets have a very strong but low magnetic field and are capable of safely lifting loads in excess of 2,000 pounds, which can be diminished under certain load conditions. These magnets are sensitive to air gaps between the magnet and the load. This means that when the air gap increases, the magnetic holding force will be reduced due to a lower density of magnetic flux between the magnet and the load. Air gaps are created in different ways. A few examples are paint, dust, and heavy mill scale. Badly machined surfaces also create air gaps. Full lifting capacity can only be obtained when the magnet makes full contact with the material being lifted.
Permanent lifting magnets do not require electrical power to operate. They are operated manually with a lever mounted on the lifter. However, they cannot be operated remotely. Permanent lifting magnets are easy to operate. With the lever in the off position, the load should be placed on the lifter, eliminating as many air gaps as possible. When the magnetizing lever is placed in the “on” position, the load will be magnetized and ready for lifting. Attempt a trial lift to ensure the load can be lifted safely. When the lift is completed, and the load has been placed completely and safely in a resting position, move the lever to the “off” position to release the load from the lifter. For long and heavy loads, multiple magnets can be used in tandem to extend the lifting capacity.
Immune to Power Failures
Failsafe operation is the unique advantage of permanent lifting magnets. They are immune to power failures. The electromagnetic lifter does not have this safety feature because electromagnets require continuous electrical power to operate. Electromagnetic lifters would require the integration of an uninterruptible power supply to produce a failsafe operation. This would, of course, increase start up, maintenance and operating costs. On the other hand, the electromagnetic lifter is the most cost-effective “magnets per pound of lift” since they can extend the lifting capacity beyond what permanent magnetic lifters can handle. The electro-permanent magnetic lifter also possesses the failsafe feature but this type of lifter requires electrical power to turn the lifter on or off. The power can be supplied by a battery. The amount of power consumption to turn the electro-permanent lifter “on” or “off” is nominal. However, the battery will need to be charged periodically.