UMT 12x20 orange / N38 - board holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their exceptional pulling force, neodymium magnets offer the following advantages:

• They retain their attractive force for around 10 years – the loss is just ~1% (according to analyses),
• They remain magnetized despite exposure to magnetic noise,
• The use of a polished nickel surface provides a smooth finish,
• They exhibit superior levels of magnetic induction near the outer area 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 shape),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which increases their usage potential,
• Key role in modern technologies – they are utilized in computer drives, electric motors, healthcare devices along with high-tech tools,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and reinforces its overall durability,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent decline 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,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, it's best to use waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is restricted,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is important in the protection of children. It should also be noted that tiny components from these products have the potential to hinder health screening once in the system,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Maximum holding power of the magnet – what contributes to it?

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

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a refined outer layer
• with zero air gap
• with vertical force applied
• at room temperature

Determinants of practical lifting force of a magnet

Practical lifting force is dependent on factors, listed from the most critical to the less significant:

• 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.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.