MW 100x10 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during nearly ten years – the reduction of lifting capacity is only ~1% (according to tests),
• They remain magnetized despite exposure to magnetic noise,
• The use of a decorative silver surface provides a refined finish,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• 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 application range,
• Significant impact in cutting-edge sectors – they are used in hard drives, electromechanical systems, healthcare devices or even other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to external force, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage while also reinforces its overall robustness,
• They lose field intensity at high 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,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of rubber for outdoor use,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Potential hazard from tiny pieces may arise, especially if swallowed, which is crucial in the context of child safety. Furthermore, tiny components from these magnets may complicate medical imaging when ingested,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Breakaway strength of the magnet in ideal conditions – what affects it?

The given strength of the magnet corresponds to the optimal strength, calculated under optimal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is affected by these factors, arranged from the most important to the least relevant:

• 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 a perpendicular force was applied, however under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.