SM 25x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
• They protect against demagnetization induced by ambient magnetic influence very well,
• The use of a decorative nickel surface provides a eye-catching finish,
• The outer field strength of the magnet shows elevated magnetic properties,
• Neodymium magnets are known for strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• With the option for fine forming and precise design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Key role in advanced technical fields – they are used in hard drives, electric motors, medical equipment and technologically developed systems,
• 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 neodymium magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to shocks, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time strengthens its overall strength,
• They lose field intensity at high temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of synthetic coating for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing holes directly in the magnet,
• Possible threat from tiny pieces may arise, especially if swallowed, which is important in the health of young users. Additionally, miniature parts from these devices can complicate medical imaging if inside the body,
• Due to expensive raw materials, their cost is above average,

Magnetic strength at its maximum – what affects it?

The given strength of the magnet represents the optimal strength, measured in ideal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet is influenced by in practice the following factors, from primary to secondary:

• Air gap between the magnet and the plate, because 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, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.