BM 850x180x70 [4x M8] - magnetic beam

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They do not lose their magnetism, even after around ten years – the decrease of lifting capacity is only ~1% (according to tests),
• They show superior resistance to demagnetization from external field exposure,
• By applying a reflective layer of silver, the element gains a clean look,
• They exhibit extremely high levels of magnetic induction near the outer area of the magnet,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the structure),
• The ability for custom shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Wide application in modern technologies – they are utilized in data storage devices, electric motors, clinical machines as well as high-tech tools,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time increases its overall resistance,
• They lose strength at high temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to humidity can degrade. Therefore, for outdoor applications, we suggest waterproof types made of non-metallic composites,
• Limited ability to create internal holes in the magnet – the use of a magnetic holder is recommended,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is important in the family environments. Furthermore, tiny components from these products have the potential to interfere with diagnostics if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Optimal lifting capacity of a neodymium magnet – what affects it?

The given strength of the magnet means the optimal strength, measured in the best circumstances, specifically:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a polished side
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Practical lifting capacity: influencing factors

The lifting capacity of a magnet is influenced by in practice the following factors, according to their importance:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.