UMC 20x6/3x7 / N38 - cylindrical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (in testing),
• They are highly resistant to demagnetization caused by external field interference,
• By applying a reflective layer of gold, the element gains a sleek look,
• They have exceptional magnetic induction on the surface of the magnet,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• The ability for accurate shaping as well as customization to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Wide application in advanced technical fields – they find application in computer drives, rotating machines, medical equipment or even high-tech tools,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and enhances its overall robustness,
• They lose field intensity at increased temperatures. Most neodymium magnets experience permanent degradation 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,
• They rust in a humid environment – during outdoor use, we recommend using moisture-resistant magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing threads directly in the magnet,
• Possible threat related to magnet particles may arise, especially if swallowed, which is crucial in the family environments. Moreover, tiny components from these devices may complicate medical imaging when ingested,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Maximum lifting force for a neodymium magnet – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, determined in the best circumstances, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

Practical lifting capacity: influencing factors

The lifting capacity of a magnet depends on in practice key elements, according to their importance:

• Air gap between the magnet and the plate, because 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 by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate lowers the lifting capacity.