MW 25x2.5 / N38 - cylindrical 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 strength, because even after 10 years, the performance loss is only ~1% (in laboratory conditions),
• Their ability to resist magnetic interference from external fields is notable,
• In other words, due to the shiny gold coating, the magnet obtains an stylish appearance,
• They exhibit extremely high levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for customized forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Wide application in cutting-edge sectors – they are used in computer drives, electric drives, medical equipment and technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of magnetic elements:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time strengthens its overall durability,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on shape). 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,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of synthetic coating for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing holes directly in the magnet,
• Potential hazard due to small fragments may arise, especially if swallowed, which is crucial in the family environments. Moreover, tiny components from these products can interfere with diagnostics once in the system,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

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

The given holding capacity of the magnet corresponds to the highest holding force, assessed in the best circumstances, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Lifting capacity in practice – influencing factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, in descending order of importance:

• 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.

* Lifting capacity was determined with the use of a smooth steel plate of suitable thickness (min. 20 mm), under vertically applied force, whereas under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the holding force.