MW 12x50 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their superior power, neodymium magnets have these key benefits:

• They virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (according to literature),
• They show exceptional resistance to demagnetization from external field exposure,
• By applying a bright layer of nickel, the element gains a clean look,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the structure),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Wide application in advanced technical fields – they find application in data storage devices, electric drives, clinical machines along with other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them ideal in miniature devices

Disadvantages of neodymium magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to physical collisions, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally reinforces its overall robustness,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent decline 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of synthetic coating for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing threads directly in the magnet,
• Possible threat related to magnet particles may arise, especially if swallowed, which is notable in the family environments. It should also be noted that miniature parts from these devices might disrupt scanning once in the system,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured in a perfect environment, specifically:

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

Lifting capacity in real conditions – factors

Practical lifting force is determined by factors, by priority:

• Air gap between the magnet and the plate, since 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 measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate decreases the holding force.