SM 25x150 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during nearly ten years – the reduction of strength is only ~1% (according to tests),
• They remain magnetized despite exposure to magnetic surroundings,
• By applying a bright layer of nickel, the element gains a sleek look,
• The outer field strength of the magnet shows advanced magnetic properties,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which increases their usage potential,
• Important function in cutting-edge sectors – they serve a purpose in HDDs, electromechanical systems, clinical machines and high-tech tools,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They can break when subjected to a strong impact. If the magnets are exposed to shocks, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from breakage while also reinforces its overall resistance,
• They lose power at increased temperatures. Most neodymium magnets experience permanent loss 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 humidity can rust. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Limited ability to create complex details 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 notable in the health of young users. It should also be noted that miniature parts from these magnets can hinder health screening when ingested,
• Due to a complex production process, their cost is above average,

Best holding force of the magnet in ideal parameters – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, determined in a perfect environment, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• in a perpendicular direction of force
• in normal thermal conditions

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is affected by these factors, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, as 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 tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the holding force.