MW 8x8 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetism, neodymium magnets have these key benefits:

• They retain their magnetic properties for nearly 10 years – the loss is just ~1% (based on simulations),
• They protect against demagnetization induced by surrounding magnetic fields effectively,
• In other words, due to the metallic nickel coating, the magnet obtains an stylish appearance,
• They possess strong magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for tailored forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Significant impact in cutting-edge sectors – they are used in HDDs, rotating machines, medical equipment along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them useful in miniature devices

Disadvantages of magnetic elements:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to external force, 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 at the same time strengthens its overall robustness,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can rust. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing threads directly in the magnet,
• Potential hazard from tiny pieces may arise, especially if swallowed, which is notable in the protection of children. Moreover, miniature parts from these magnets can complicate medical imaging when ingested,
• Due to expensive raw materials, their cost is relatively high,

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

The given holding capacity of the magnet corresponds to the highest holding force, measured under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• with zero air gap
• with vertical force applied
• under standard ambient temperature

What influences lifting capacity in practice

The lifting capacity of a magnet is determined by in practice the following factors, ordered from most important to least significant:

• 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 was assessed with the use of a smooth steel plate of suitable thickness (min. 20 mm), under vertically applied force, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet and the plate decreases the load capacity.