KM HF - 11,3 kg - magnetic bracket

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• They do not lose their even during nearly 10 years – the reduction of lifting capacity is only ~1% (according to tests),
• They protect against demagnetization induced by external magnetic fields remarkably well,
• Thanks to the shiny finish and silver coating, they have an aesthetic appearance,
• Magnetic induction on the surface of these magnets is very strong,
• With the right combination of magnetic alloys, they reach increased thermal stability, enabling operation at or above 230°C (depending on the design),
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their usage potential,
• Important function in new technology industries – they find application in computer drives, electromechanical systems, diagnostic apparatus along with high-tech tools,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, in miniature format,

Disadvantages of magnetic elements:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and strengthens its overall durability,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on shape). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• They rust in a moist environment, especially when used outside, we recommend using waterproof magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing complex structures directly in the magnet,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is important in the protection of children. Moreover, miniature parts from these assemblies might disrupt scanning when ingested,
• Due to the price of neodymium, their cost is above average,

Best holding force of the magnet in ideal parameters – what it depends on?

The given lifting capacity of the magnet represents the maximum lifting force, assessed in a perfect environment, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Lifting capacity in real conditions – factors

Practical lifting force is determined by factors, by priority:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes 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.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as fivefold. Additionally, even a small distance {between} the magnet and the plate decreases the lifting capacity.