Handling Magnets

Handling magnets are used for transport, transfer, fastening and lifting of ferromagnetic products in the metal, automotive and robot industry. Magnetic handling of products reduces both the time it takes and the number of actions required to automate a process and ensure it proceeds smoothly.

To automate these processes, Goudsmit Magnetics Group has developed an extensive range of magnetic systems. Various processes that have been tested handling, lifting, transport and fastening. The features of these are detailed below;

Handling

• Lifting sheets or steel products in the automotive/robotic industries;
• Automatic robot handling of both flat, formed or perforated steel sheets;
• Separating the top sheet from a stack: This is important for thin sheets as this process prevents a robot from grabbing multiple sheets at the same time;
• Uniform alignment of nails or screws. This reduces packaging volume.

Lifting

• Manually picking up small workpieces to injuries from sharp burrs;
• Moving heavy steel objects with a crane.

Transport

• Automation of packing lines. This could be useful for packing lines with tins or glass jars with steel lids are placed in boxes or on pallets;
• Horizontal, vertical or hanging transport of steel products such as tins, lids, sheets, pipes or shafts over larger distances;
• Horizontal or steeply sloping transport of small, sharp objects such as punching waste, nails or screws. This could be useful to prevent belt wear.

Fastening

• securing moulds or workpieces for welding, grinding, polishing or assembly.

Goudsmit Magnetics Group has both permanent magnets and electromagnets. It should be noted that both types of magnets are switchable, however there is an important difference:

• permanent magnets are compact and always function;
• electromagnets switch quickly and without wear, however there is a risk of the load falling if the power is interrupted. This means that electrical lifting magnets must always be equipped with a backup system, which can be expensive.

Permanent magnets can have either monostable or bistable systems. All Goudsmit lifting systems are bistable, except for the electropermanent lifting magnet type EHPM.

Unlike monostable magnet systems which are only kept activated or deactivated if that are supplied with and an electrical switching signal, a bistable magnet system is switched on and off by a switching signal and remains in that state until the following switching signal is received. For lifting and hoisting applications a bistable system is safer than one that is monostable, because it actually switches off, so it cannot unexpectedly attract a steel sheet. Bistable magnetic systems are always constructed with permanent magnets (or a combination of permanent magnets and electromagnets).

In addition to the type of magnet systems, permanent magnets also have varying switching systems. These can be electrically, pneumatically or manually switchable;

Manually switchable magnets consist of two magnets, one of which can be moved by means of a handle. In the off position the magnets are shorted, this means that they cancel each other out.

Magnet switched OFF

Magnet switched ON

Pneumatically switchable magnets are moved in an enclosure by means of compressed air so that no magnetism is present outside the enclosure in the off position, only in the on position.

Working principle of magnetic gripper

The specified maximum breakaway force of lifting and handling magnets applies for a flat sheet of at least a specific thickness. It is obvious that less force is required if the sheet is thinner or if it has a rougher or dustier surface. However, in practice, the maximum holding force is not always feasible.

For the recommended workload a safety factor should also be included. This is in accordance with the EN 13155 standard. The factor depends on the magnet system;

• Factor 2 for electromagnets and vacuum;
• Factor 3 for permanent and electro-permanent systems.

Always ensure that no one walks under a lifted load. If this cannot be prevented, there must always be an additional mechanical support or fall protector around the load.

When considering loads that will be lifted by persons, you must keep in mind the applicable guidelines for lifting and dragging:

This information has been sourced, reviewed and adapted from materials provided by Goudsmit Magnetics Group.

For more information on this source, please visit Goudsmit Magnetics Group.