SMZR 32x200 / N52 - magnetic separator with handle

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain their full power for around ten years – the drop is just ~1% (according to analyses),
• They remain magnetized despite exposure to magnetic surroundings,
• The use of a polished nickel surface provides a eye-catching finish,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of materials, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the design),
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their usage potential,
• Wide application in new technology industries – they find application in hard drives, electromechanical systems, medical equipment along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which makes them ideal in miniature devices

Disadvantages of NdFeB magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall durability,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on form). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of synthetic coating for outdoor use,
• Limited ability to create precision features in the magnet – the use of a external casing is recommended,
• Possible threat due to small fragments may arise, in case of ingestion, which is significant in the health of young users. Additionally, miniature parts from these devices have the potential to disrupt scanning once in the system,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Detachment force of the magnet in optimal conditions – what it depends on?

The given pulling force of the magnet means the maximum force, calculated in a perfect environment, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – 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, 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 conducted on plates with a smooth surface of optimal thickness, under perpendicular forces, however under shearing force the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the holding force.