SM 25x150 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their magnetic properties for around ten years – the loss is just ~1% (based on simulations),
• They protect against demagnetization induced by ambient magnetic influence very well,
• The use of a decorative nickel surface provides a eye-catching finish,
• They possess strong magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for precise shaping as well as adjustment to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in advanced technical fields – they find application in data storage devices, electromechanical systems, healthcare devices or even sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them useful in small systems

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time enhances its overall strength,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can corrode. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing complex structures directly in the magnet,
• Possible threat linked to microscopic shards may arise, especially if swallowed, which is crucial in the family environments. Furthermore, small elements from these devices might complicate medical imaging if inside the body,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The given lifting capacity of the magnet represents the maximum lifting force, determined in ideal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• in normal thermal conditions

Key elements affecting lifting force

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, because 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 was assessed by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, however under shearing force the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.