SM 32x275 [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 strength approximately ten years – the decrease of strength is only ~1% (based on measurements),
• Their ability to resist magnetic interference from external fields is impressive,
• By applying a reflective layer of silver, the element gains a clean look,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Thanks to their exceptional temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their application range,
• Wide application in new technology industries – they find application in data storage devices, rotating machines, medical equipment as well as other advanced devices,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to physical collisions, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks and additionally strengthens its overall durability,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on size). 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,
• Magnets exposed to damp air can rust. Therefore, for outdoor applications, we advise waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is restricted,
• Potential hazard related to magnet particles may arise, especially if swallowed, which is notable in the protection of children. It should also be noted that small elements from these products might interfere with diagnostics after being swallowed,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Detachment force of the magnet in optimal conditions – what it depends on?

The given holding capacity of the magnet means the highest holding force, assessed under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

Practical lifting force is dependent on elements, by priority:

• 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 measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the holding force.