UMC 16x5/2x5 / N38 - cylindrical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have stable power, and over nearly ten years their performance decreases symbolically – ~1% (according to theory),
• Their ability to resist magnetic interference from external fields is among the best,
• The use of a decorative nickel surface provides a refined finish,
• They possess strong magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which expands their usage potential,
• Key role in modern technologies – they find application in hard drives, rotating machines, healthcare devices as well as sophisticated instruments,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage and additionally enhances its overall strength,
• High temperatures may significantly reduce the strength 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,
• They rust in a wet environment. For outdoor use, we recommend using encapsulated magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing threads directly in the magnet,
• Potential hazard from tiny pieces may arise, if ingested accidentally, which is crucial in the family environments. Furthermore, minuscule fragments from these devices may interfere with diagnostics when ingested,
• Due to the price of neodymium, their cost is relatively high,

Best holding force of the magnet in ideal parameters – what contributes to it?

The given strength of the magnet means the optimal strength, determined in the best circumstances, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• at room temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet is influenced by in practice the following factors, ordered from most important to least significant:

• 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate decreases the lifting capacity.