UMT 12x20 orange / N38 - board holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their magnetic properties for nearly ten years – the loss is just ~1% (in theory),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the reflective layer of gold, the component looks high-end,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• The ability for precise shaping as well as adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Significant impact in advanced technical fields – they find application in HDDs, electric motors, clinical machines or even high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time reinforces its overall strength,
• They lose field intensity at high temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to wet conditions can degrade. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Health risk related to magnet particles may arise, especially if swallowed, which is crucial in the family environments. Moreover, tiny components from these magnets might interfere with diagnostics if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Magnetic strength at its maximum – what contributes to it?

The given strength of the magnet corresponds to the optimal strength, assessed in the best circumstances, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• in normal thermal conditions

Lifting capacity in practice – influencing factors

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

• Air gap between the magnet and the plate, as 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 the plate surface of 20 mm thickness, when the force acted perpendicularly, however 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.