UMGB 75x28 [M8+M10] GW F200 +Lina GOBLIN / N38 - goblin magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their immense strength, neodymium magnets offer the following advantages:

• They do not lose their power around 10 years – the reduction of lifting capacity is only ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic influence remarkably well,
• The use of a mirror-like nickel surface provides a smooth finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• With the right combination of magnetic alloys, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the design),
• Thanks to the possibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Wide application in modern technologies – they are utilized in computer drives, electromechanical systems, medical equipment as well as sophisticated instruments,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to external force, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and additionally reinforces its overall robustness,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on size). 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 humid environment – during outdoor use, we recommend using moisture-resistant magnets, such as those made of plastic,
• Limited ability to create internal holes in the magnet – the use of a magnetic holder is recommended,
• Health risk from tiny pieces may arise, especially if swallowed, which is crucial in the family environments. It should also be noted that minuscule fragments from these assemblies can interfere with diagnostics once in the system,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

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

The given holding capacity of the magnet represents the highest holding force, calculated in ideal conditions, namely:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Impact of factors on magnetic holding capacity in practice

In practice, the holding capacity of a magnet is conditioned by these factors, arranged from the most important to the least relevant:

• 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.

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