SM 25x325 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after 10 years, the performance loss is only ~1% (in laboratory conditions),
• They show superior resistance to demagnetization from outside magnetic sources,
• By applying a reflective layer of nickel, the element gains a sleek look,
• Magnetic induction on the surface of these magnets is notably high,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for customized forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Important function in advanced technical fields – they find application in computer drives, electric drives, healthcare devices as well as sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which allows for use in compact constructions

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to physical collisions, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and reinforces its overall resistance,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on height). 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 advisable to use sealed magnets made of protective material for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a external casing is recommended,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is significant in the family environments. Furthermore, miniature parts from these magnets may complicate medical imaging after being swallowed,
• Due to expensive raw materials, their cost is considerably higher,

Maximum lifting capacity of the magnet – what it depends on?

The given strength of the magnet corresponds to the optimal strength, assessed under optimal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Lifting capacity in practice – influencing factors

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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.

* Lifting capacity was determined with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate decreases the holding force.