MW 38x12 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• Their magnetic field is durable, and after approximately 10 years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by ambient magnetic influence very well,
• Because of the reflective layer of gold, the component looks high-end,
• 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,
• The ability for custom shaping and customization to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Significant impact in modern technologies – they are used in hard drives, electric motors, clinical machines or even other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in small dimensions, which allows for use in compact constructions

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to mechanical hits, 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 strengthens its overall strength,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a moist environment, especially when used outside, we recommend using encapsulated magnets, such as those made of polymer,
• Limited ability to create threads in the magnet – the use of a external casing is recommended,
• Possible threat due to small fragments may arise, in case of ingestion, which is crucial in the family environments. Additionally, miniature parts from these magnets have the potential to interfere with diagnostics if inside the body,
• In cases of mass production, neodymium magnet cost may be a barrier,

Maximum lifting force for a neodymium magnet – what affects it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured under optimal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• in normal thermal conditions

Magnet lifting force in use – key factors

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, 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 assessed by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the holding force.