Work Holding Devices Milling Machine

Magnetic Lifters for Heavy Load Operations

With a lifting capacity of exceeding 25 tons, magnetic lifters are well suited for a wide range of applications.

Magnetic lifters are an ideal material-handling solution for transporting heavy loads of ferro-magnetic material, such as steel plates, forgings and die castings, safely without the use of clamps, slings, chains and other holding devices.

Types of Magnetic Lifters

There are three types of lifting magnets: permanent, electromagnet and electro-permanent. While they all can safely transport heavy loads, each type has its application specific advantages.

Permanent magnet lifters, made from rare earth or ceramics materials, use permanently magnetized material to generate the lifter's magnetic field or holding force. They do not require electrical power, which eliminates hazards caused by power interruptions and gives them the added benefit of portability. They are manually operated using a lever located on the lifter. A safety latch is typically built in to ensure that the magnet is not accidentally turned off while performing a lift. However, one disadvantage is that permanent magnets have a non-variable lifting capacity.

Electromagnetic lifters use an energized electrical coil wound around a steel core embedded in the lifter to generate the magnetic field. A D.C. controller or rectifier provides the excitation voltage to energize the magnet. This voltage can be varied and gives the electromagnetic lifter another benefit: variable holding power. However, the primary disadvantage is they require the continuous application of electrical power to operate. So, a power failure would de-energize the magnet and create a potential safety hazard. To overcome this problem, an uninterruptible power supply (backup system) would need to be integrated into the lifting system.

Electro-permanent magnetic lifters are a combination of the permanent and electromagnetic types. They use permanent magnetic material that is turned on or off by a D.C power supply, which can be supplied by a D.C. controller or a battery, but electricity is not required at all times. The battery would require periodic recharging, however. Since they only need electrical power to turn the lifter on or off, they have a built-in failsafe operation.

Retrieving and Scrap Applications

Lifting magnets are the perfect solution for retrieving material from obscure, difficult-to-reach, or dangerous places. They are commonly used in underwater applications to retrieve metal from a damaged submerged vessel like a sunken ship or wrecked oil well. Lifting magnets in these applications are called retrieving magnets.

Larger, heavy-duty lifting magnets are often called scrap magnets. They can be used to lift large objects like scrapped vehicles. Specially designed, scrap magnets have the ability to lift large coils of wire without the unwinding or telescoping of the coil.

Other Advantages

There are many other advantages to gain from lifting magnets. They include:

Eliminate Drilling Tap Holes: the need to drill and tap holes in materials prior to lifting is many times required to obtain an anchor point or eyebolt to latch onto. In many instances after lifting, the eyebolts need to be removed and the holes filled up, which can add to the cost of the product.

Easily Palletized: Magnet lifters are particularly useful if individual parts from a stack or crate of parts need to be moved. By accessing the part with a lifting magnet, it can be lifted vertically out of the crate or stack.