Magnetic Lifters

A magnetic lifter is a component used for moving loads made of ferromagnetic materials. There are 2 types of lifters that operate based on a permanent magnetic field. Field of application: metal products, auto repair shops, construction, utility line installation. The lifter is used to move metal pipes, blanks, and automotive components.

Types of magnetic lifters

The PML lifter is available with manual or automated control. The design of the common PML model includes the following elements:

1. Body. Rectangular or rounded shape.
2. Permanent neodymium magnet, made from a rare-earth metal alloy.
3. Base with a replaceable block — used for moving products in different planes.
4. Axle that rotates in a dedicated joint.
5. Handle equipped with a rotation limiter.
6. Load ring for attaching to a crane.

Materials

The magnetic component consists of:

1. Rare-earth metals.
2. Iron.
3. Cobalt.
4. Aluminium.
5. Niobium.

Adding up to 36% rare-earth elements increases the alloy’s magnetization up to 1500 mT. Niobium increases resistance to temperature and oxidizers.

To extend the service life, the magnet is covered with an additional layer of anti-corrosion material: nickel plating or zinc plating.

Magnetic elements are divided into 4 classes by corrosion resistance. The first withstands temperatures up to 80°C, the fourth — up to 150°C.

Operating principle

The base is positioned so that it contacts the adjacent surface along the maximum diagonal. The lifter with the ring is then attached to the hook of the lifting mechanism. After lowering the hook, the lifter and the magnet are engaged by aligning the rotation of the eccentric axle.

Several types of PML lifters are distinguished by their marking. The load capacity is indicated in the numerical designation of the marking and applies only to a flat surface. For a curved surface, the total load capacity is halved.

Marking examples:

1. PML 100.
2. PML 300.
3. PML 600.
4. PML 1000.

According to manufacturers’ regulations, safety at the moment of detachment is achieved with a load capacity margin exceeding 350% of the rated value. Before use, contact surfaces are cleaned of defects.

Pulse and automatic systems for sheet metal

For metal structures over 70 mm thick and slabs with a temperature from 50°C, it is more effective to use magnetic lifters with constant or pulse activity. They are more flexible: the magnetic field makes denser contact with the surface being lifted due to the magnetic transfer used to close the halves together.

Automatic lifters increase the contact area between the magnet and the metal surface, so they are used in spreader beams for moving blanks longer than 200 cm. The lifter is activated by the tension of the hook with slings — personnel do not need to activate it manually.

How to choose

Characteristics affecting operation, besides load capacity:

1. Length and rotation angle of the handle.
2. Temperature parameters of the blanks to be moved.
3. Type of bracket: the presence of a hinged mechanism increases reliability and flexibility of attachment.
4. Material of the blanks. The material has a load capacity safety factor. For example, for a cast-iron beam weighing 400 kg with a factor of 0.5, a PML1000 lifter is required — a PML600 would be insufficient.

Dimensions of the loads being moved: for metal elements longer than 600 cm, it is advisable to use special spreader beams.