UMT 12x20 black / N38 - board holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (according to literature),
• They protect against demagnetization induced by surrounding magnetic influence effectively,
• By applying a reflective layer of nickel, the element gains a clean look,
• They exhibit superior 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,
• The ability for custom shaping or customization to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Significant impact in advanced technical fields – they are used in computer drives, electric motors, clinical machines or even technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage and additionally increases its overall robustness,
• They lose strength at high temperatures. Most neodymium magnets experience permanent reduction 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,
• They rust in a damp environment, especially when used outside, we recommend using sealed magnets, such as those made of rubber,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing holes directly in the magnet,
• Safety concern due to small fragments may arise, in case of ingestion, which is notable in the health of young users. It should also be noted that tiny components from these assemblies may disrupt scanning if inside the body,
• Due to expensive raw materials, their cost is relatively high,

Highest magnetic holding force – what it depends on?

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

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Magnet lifting force in use – key 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) 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 assessed with the use of a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.