SM 18x125 [2xM5] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their remarkable magnetic power, neodymium magnets offer the following advantages:

• They retain their magnetic properties for nearly 10 years – the loss is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a shiny layer of gold, the element gains a modern look,
• Magnetic induction on the surface of these magnets is notably high,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the structure),
• The ability for custom shaping or customization to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which enhances their versatility in applications,
• Significant impact in modern technologies – they are used in HDDs, electromechanical systems, healthcare devices along with other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on size). 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 wise to use sealed magnets made of plastic for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Potential hazard due to small fragments may arise, in case of ingestion, which is crucial in the health of young users. It should also be noted that minuscule fragments from these products might disrupt scanning after being swallowed,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Maximum lifting force for a neodymium magnet – what it depends on?

The given pulling force of the magnet represents the maximum force, measured in ideal conditions, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Impact of factors on magnetic holding capacity in practice

Practical lifting force is determined by factors, by priority:

• 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.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the holding force is lower. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.