MW 5x10 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable magnetic power, neodymium magnets offer the following advantages:

• They retain their full power for around 10 years – the loss is just ~1% (in theory),
• They remain magnetized despite exposure to magnetic surroundings,
• Because of the reflective layer of nickel, the component looks visually appealing,
• They exhibit extremely high levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which increases their usage potential,
• Key role in modern technologies – they are used in hard drives, rotating machines, healthcare devices or even other advanced devices,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture while also enhances its overall robustness,
• High temperatures may significantly reduce the magnetic power of neodymium magnets. Typically, above 80°C, they experience permanent weakening in performance (depending on size). 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 wet environment. For outdoor use, we recommend using waterproof magnets, such as those made of rubber,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Possible threat from tiny pieces may arise, in case of ingestion, which is significant in the context of child safety. Additionally, tiny components from these products may complicate medical imaging if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

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

The given holding capacity of the magnet means the highest holding force, calculated under optimal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• under perpendicular detachment force
• at room temperature

Lifting capacity in practice – influencing factors

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• 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 determined by applying a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.