BM 550x180x70 [4x M8] - magnetic beam

Strengths and weaknesses of rare earth magnets.

Besides their tremendous strength, neodymium magnets offer the following advantages:

• They do not lose power, even over approximately 10 years – the reduction in lifting capacity is only ~1% (based on measurements),
• They are extremely resistant to demagnetization induced by external disturbances,
• A magnet with a metallic nickel surface has better aesthetics,
• Magnetic induction on the working part of the magnet is exceptional,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to freedom in forming and the ability to adapt to specific needs,
• Significant place in innovative solutions – they serve a role in computer drives, electromotive mechanisms, medical devices, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which allows their use in compact constructions

Disadvantages of NdFeB magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• Due to limitations in realizing threads and complicated forms in magnets, we propose using a housing - magnetic mount.
• Health risk related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these products can complicate diagnosis medical after entering the body.
• Due to neodymium price, their price is relatively high,

Maximum holding power of the magnet – what it depends on?

The load parameter shown concerns the limit force, measured under optimal environment, specifically:

• using a base made of mild steel, acting as a circuit closing element
• possessing a massiveness of min. 10 mm to avoid saturation
• characterized by even structure
• without any clearance between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at ambient temperature room level

Practical lifting capacity: influencing factors

Holding efficiency impacted by working environment parameters, such as (from most important):

• Gap (betwixt the magnet and the plate), because even a tiny distance (e.g. 0.5 mm) can cause a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Load vector – highest force is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is usually many times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin plate does not close the flux, causing part of the flux to be escaped to the other side.
• Plate material – mild steel gives the best results. Alloy steels reduce magnetic properties and holding force.
• Surface quality – the more even the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Thermal factor – high temperature reduces magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as 5 times. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.