UMC 25x6/4x8 / N38 - cylindrical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent magnetic energy, neodymium magnets have these key benefits:

• They have constant strength, and over around 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They protect against demagnetization induced by surrounding electromagnetic environments effectively,
• Because of the brilliant layer of silver, the component looks visually appealing,
• They have exceptional magnetic induction on the surface of the magnet,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• Thanks to the freedom in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their functional possibilities,
• Key role in cutting-edge sectors – they find application in data storage devices, electric drives, medical equipment as well as sophisticated instruments,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage while also enhances its overall durability,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to moisture can degrade. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Potential hazard linked to microscopic shards may arise, when consumed by mistake, which is significant in the family environments. Furthermore, minuscule fragments from these assemblies can interfere with diagnostics when ingested,
• High unit cost – neodymium magnets are pricier 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 lifting capacity of the magnet means the maximum lifting force, measured in the best circumstances, specifically:

• with mild steel, used 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
• under standard ambient temperature

Key elements affecting lifting force

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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 carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet and the plate reduces the holding force.