BM 380x180x70 [4x M8] - magnetic beam

Advantages as well as disadvantages of rare earth magnets.

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

• They have unchanged lifting capacity, and over nearly ten years their attraction force decreases symbolically – ~1% (in testing),
• Neodymium magnets are characterized by exceptionally resistant to magnetic field loss caused by external field sources,
• Thanks to the glossy finish, the surface of nickel, gold-plated, or silver gives an clean appearance,
• The surface of neodymium magnets generates a strong magnetic field – this is a distinguishing feature,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for functioning at temperatures approaching 230°C and above...
• Possibility of accurate creating and adapting to individual applications,
• Fundamental importance in modern technologies – they are utilized in magnetic memories, electromotive mechanisms, medical devices, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in small systems

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest casing - magnetic mechanism, due to difficulties in producing threads inside the magnet and complex shapes.
• Health risk resulting from small fragments of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. Additionally, tiny parts of these devices can be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum magnetic pulling force – what contributes to it?

Magnet power was determined for the most favorable conditions, assuming:

• with the contact of a sheet made of special test steel, ensuring full magnetic saturation
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a plane perfectly flat
• with zero gap (without coatings)
• during pulling in a direction vertical to the plane
• in neutral thermal conditions

Practical aspects of lifting capacity – factors

Effective lifting capacity is affected by working environment parameters, such as (from priority):

• Distance – the presence of any layer (rust, tape, gap) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Plate material – mild steel attracts best. Alloy steels lower magnetic permeability and holding force.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Thermal factor – hot environment reduces magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.