BM 550x180x70 [4x M8] - magnetic beam

Advantages as well as disadvantages of neodymium magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They do not lose power, even over nearly ten years – the reduction in lifting capacity is only ~1% (theoretically),
• Neodymium magnets are characterized by highly resistant to magnetic field loss caused by external interference,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• The surface of neodymium magnets generates a concentrated magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in constructing and the capacity to adapt to unusual requirements,
• Versatile presence in electronics industry – they are commonly used in HDD drives, electromotive mechanisms, advanced medical instruments, also modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in compact constructions

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a special holder, which not only protects them against impacts but also raises their durability
• Neodymium magnets decrease their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• We suggest casing - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated shapes.
• Potential hazard resulting from small fragments of magnets can be dangerous, if swallowed, which becomes key in the context of child safety. Additionally, small elements of these devices are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

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

Magnet power was determined for optimal configuration, taking into account:

• on a base made of mild steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• characterized by even structure
• with direct contact (without coatings)
• for force applied at a right angle (in the magnet axis)
• at ambient temperature room level

Practical aspects of lifting capacity – factors

Bear in mind that the application force will differ depending on elements below, in order of importance:

• Gap (between the magnet and the metal), as even a tiny clearance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to varnish, rust or dirt).
• Force direction – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Plate material – mild steel attracts best. Alloy steels reduce magnetic properties and lifting capacity.
• Surface condition – ground elements ensure maximum contact, which increases force. Rough surfaces reduce efficiency.
• Thermal factor – high temperature reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate lowers the lifting capacity.