What Is a Lifting Magnet?
A lifting magnet is a device that attracts objects using magnetic force.
Lifting magnets are typically attached to moving equipment, such as robot arms, and are used for lifting and transporting objects that can be attracted by magnets.
They find extensive use in factories handling iron products because, unlike two-finger parallel grippers, they are not restricted by the shape of the object they can grip and can adhere to objects with one or more flat surfaces.
Uses of Lifting Magnets
Lifting magnets employ magnetic force to adhere to objects and come in two types: electromagnetic and permanent magnet.
Electromagnetic lifting magnets are used in equipment that transports a fixed number of steel plates because the strength of the magnetic force can be freely adjusted.
Permanent magnetic lifting magnets do not require electrical equipment such as wiring or rectifiers and are thus utilized at the end of relatively small hand cranes or as chucking mechanisms on work tables.
Many permanent magnet types are of the permanent electromagnetic variety, where only the ON/OFF switching operation is electrically driven. They are advantageous in preventing accidents during power failures and consuming less power.
Principle of Lifting Magnets
Electromagnetic lifting magnets are equipped with an electromagnet inside that attracts objects when energized. The force of attraction can be adjusted by controlling the current flow through the electromagnet.
Permanent magnet-type lifting magnets have a fixed permanent magnet inside. The magnet’s suction force is activated by manually rotating the magnet’s direction by 90 degrees, typically done using an electric device like a servo motor.
Since lifting magnets rely on magnetic force to adhere to objects, they can securely grip objects made mainly of magnetic materials such as iron, cobalt, and nickel. However, when trying to grip objects made of materials with more than one primary component, like alloys, caution must be exercised as the gripping force may vary based on the material’s composition.
Materials like aluminum, which are not magnetic, cannot be gripped by lifting magnets. In contrast, stainless steel, which is an iron alloy, can be gripped or not gripped depending on the specific type. Austenitic SUS304 stainless steel, commonly used, cannot be gripped, but ferritic or martensitic stainless steel can be gripped. The appropriate lifting magnet must be selected based on the material of the object to be gripped.