MP 5x2.7/1.2x5 Z / N38 - ring magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• They are very resistant to demagnetization caused by external field interference,
• In other words, due to the metallic gold coating, the magnet obtains an stylish appearance,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• With the option for customized forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Key role in advanced technical fields – they serve a purpose in computer drives, electric drives, healthcare devices and technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which makes them useful in miniature devices

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to external force, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time enhances its overall strength,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on form). 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 – during outdoor use, we recommend using moisture-resistant magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing holes directly in the magnet,
• Possible threat related to magnet particles may arise, when consumed by mistake, which is important in the context of child safety. It should also be noted that minuscule fragments from these devices have the potential to hinder health screening after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Breakaway strength of the magnet in ideal conditions – what it depends on?

The given holding capacity of the magnet represents the highest holding force, determined in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• with vertical force applied
• under standard ambient temperature

Lifting capacity in real conditions – factors

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

• Air gap between the magnet and the plate, since 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 the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.