SMZR 25x175 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their stability, neodymium magnets are valued for these benefits:

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• They are highly resistant to demagnetization caused by external field interference,
• The use of a decorative silver surface provides a smooth finish,
• The outer field strength of the magnet shows advanced magnetic properties,
• 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 specific requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their functional possibilities,
• Significant impact in advanced technical fields – they are utilized in hard drives, electromechanical systems, healthcare devices and technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to physical collisions, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage and additionally reinforces its overall strength,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of rubber for outdoor use,
• Limited ability to create complex details in the magnet – the use of a external casing is recommended,
• Potential hazard linked to microscopic shards may arise, in case of ingestion, which is crucial in the context of child safety. Additionally, small elements from these devices have the potential to disrupt scanning when ingested,
• In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

Maximum lifting capacity of the magnet – what affects it?

The given pulling force of the magnet corresponds to the maximum force, assessed in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• under perpendicular detachment force
• under standard ambient temperature

Lifting capacity in real conditions – factors

The lifting capacity of a magnet is determined by in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, since 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 testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. Moreover, even a minimal clearance {between} the magnet and the plate decreases the load capacity.