UMS 20x8.6x4.5x7 / N38 - conical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after 10 years, the performance loss is only ~1% (based on calculations),
• They show strong resistance to demagnetization from external magnetic fields,
• In other words, due to the shiny nickel coating, the magnet obtains an stylish appearance,
• They possess significant 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,
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in various configurations, which increases their functional possibilities,
• Key role in modern technologies – they are used in computer drives, electromechanical systems, medical equipment and high-tech tools,
• Thanks to their power density, small magnets offer high magnetic performance, in miniature format,

Disadvantages of magnetic elements:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to mechanical hits, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and additionally enhances its overall strength,
• They lose strength at elevated 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,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of plastic for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing complex structures directly in the magnet,
• Potential hazard related to magnet particles may arise, in case of ingestion, which is significant in the health of young users. Furthermore, small elements from these products may disrupt scanning after being swallowed,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Magnetic strength at its maximum – what affects it?

The given holding capacity of the magnet corresponds to the highest holding force, calculated in ideal conditions, specifically:

• 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 polished side
• with no separation
• in a perpendicular direction of force
• at room temperature

Lifting capacity in practice – influencing factors

Practical lifting force is determined by elements, 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) 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 measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.