MW 2x4 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous strength, neodymium magnets offer the following advantages:

• They retain their full power for almost 10 years – the drop is just ~1% (in theory),
• They are highly resistant to demagnetization caused by external magnetic fields,
• The use of a mirror-like silver surface provides a eye-catching finish,
• Magnetic induction on the surface of these magnets is impressively powerful,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for accurate shaping or customization to custom needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Key role in modern technologies – they find application in HDDs, electric drives, medical equipment or even other advanced devices,
• 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 neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens 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 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,
• Magnets exposed to damp air can rust. Therefore, for outdoor applications, it's best to use waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Health risk linked to microscopic shards may arise, especially if swallowed, which is significant in the family environments. Moreover, small elements from these magnets may hinder health screening after being swallowed,
• Due to expensive raw materials, their cost is considerably higher,

Maximum lifting force for a neodymium magnet – what it depends on?

The given strength of the magnet corresponds to the optimal strength, assessed in the best circumstances, that is:

• with mild steel, used as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• in a perpendicular direction of force
• at room temperature

Lifting capacity in practice – influencing factors

Practical lifting force is dependent on factors, by priority:

• Air gap between the magnet and the plate, because 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 checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.