UMP 94x40 [3xM10] GW F550 Silver Black Lina / N52 - search holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their remarkable magnetic power, neodymium magnets offer the following advantages:

• They do not lose their even over nearly 10 years – the loss of lifting capacity is only ~1% (based on measurements),
• Their ability to resist magnetic interference from external fields is impressive,
• Because of the reflective layer of silver, the component looks high-end,
• Magnetic induction on the surface of these magnets is impressively powerful,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• Thanks to the possibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which increases their usage potential,
• Important function in advanced technical fields – they serve a purpose in HDDs, electric motors, healthcare devices as well as technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time reinforces its overall strength,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on height). 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,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we recommend waterproof types made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing threads directly in the magnet,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is significant in the family environments. Additionally, small elements from these magnets may hinder health screening if inside the body,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Highest magnetic holding force – what contributes to it?

The given strength of the magnet represents the optimal strength, calculated under optimal conditions, namely:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a polished side
• in conditions of no clearance
• with vertical force applied
• at room temperature

Lifting capacity in real conditions – factors

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

• Air gap between the magnet and the plate, as 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 the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. Moreover, even a minimal clearance {between} the magnet and the plate reduces the holding force.