SM 32x100 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• Their power is durable, and after around ten years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic fields very well,
• The use of a mirror-like silver surface provides a eye-catching finish,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Significant impact in modern technologies – they are used in hard drives, rotating machines, clinical machines along with other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to shocks, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks and additionally strengthens its overall strength,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on shape). 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,
• They rust in a moist environment – during outdoor use, we recommend using waterproof magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is risky,
• Health risk related to magnet particles may arise, in case of ingestion, which is significant in the family environments. Furthermore, minuscule fragments from these products may hinder health screening after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost may not be economically viable,

Magnetic strength at its maximum – what it depends on?

The given holding capacity of the magnet means the highest holding force, measured in the best circumstances, 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
• at room temperature

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet is determined by in practice key elements, ordered from most important to least 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 was assessed by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the holding force.