MW 12x2 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (according to theory),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the brilliant layer of gold, the component looks visually appealing,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• With the option for fine forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Important function in new technology industries – they are utilized in data storage devices, electric motors, healthcare devices as well as other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, in miniature format,

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks while also reinforces its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening 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,
• Magnets exposed to moisture can corrode. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Limited ability to create threads in the magnet – the use of a external casing is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is notable in the context of child safety. Additionally, miniature parts from these assemblies have the potential to disrupt scanning if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Detachment force of the magnet in optimal conditions – what contributes to it?

The given holding capacity of the magnet represents the highest holding force, measured in ideal conditions, specifically:

• with mild steel, used as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Lifting capacity in real conditions – factors

In practice, the holding capacity of a magnet is affected by these factors, in descending order of importance:

• 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.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.