SM 25x200 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their consistent magnetism, neodymium magnets have these key benefits:

• Their strength is maintained, and after approximately 10 years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic influence effectively,
• Thanks to the shiny finish and silver coating, they have an aesthetic appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• With the option for tailored forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Significant impact in cutting-edge sectors – they serve a purpose in hard drives, electric drives, medical equipment as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them ideal in miniature devices

Disadvantages of rare earth magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and enhances its overall durability,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment. For outdoor use, we recommend using waterproof magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing fine shapes directly in the magnet,
• Possible threat from tiny pieces may arise, especially if swallowed, which is important in the protection of children. It should also be noted that small elements from these products might interfere with diagnostics once in the system,
• Due to a complex production process, their cost is considerably higher,

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

The given lifting capacity of the magnet corresponds to the maximum lifting force, determined in ideal conditions, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

What influences lifting capacity in practice

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

• Air gap between the magnet and the plate, since 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.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.