MW 10x5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• Their strength is maintained, and after approximately ten years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by external magnetic fields remarkably well,
• Thanks to the polished finish and gold coating, they have an visually attractive appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• With the right combination of compounds, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• The ability for custom shaping as well as adaptation to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Key role in cutting-edge sectors – they are utilized in data storage devices, electric drives, diagnostic apparatus and sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which allows for use in compact constructions

Disadvantages of rare earth magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to shocks, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks and enhances its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline 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 moist environment, especially when used outside, we recommend using waterproof magnets, such as those made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing threads directly in the magnet,
• Possible threat due to small fragments may arise, especially if swallowed, which is significant in the health of young users. Furthermore, minuscule fragments from these products can disrupt scanning after being swallowed,
• In cases of mass production, neodymium magnet cost is a challenge,

Maximum magnetic pulling force – what contributes to it?

The given strength of the magnet means the optimal strength, assessed in ideal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Lifting capacity in practice – influencing 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, as 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 tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a small distance {between} the magnet and the plate decreases the lifting capacity.