SM 32x300 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their remarkable pulling force, neodymium magnets offer the following advantages:

• They have constant strength, and over around ten years their performance decreases symbolically – ~1% (according to theory),
• They protect against demagnetization induced by ambient magnetic fields remarkably well,
• The use of a mirror-like gold surface provides a eye-catching finish,
• They possess strong magnetic force measurable at the magnet’s surface,
• 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 shape),
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Wide application in new technology industries – they serve a purpose in data storage devices, electric drives, diagnostic apparatus as well as other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB 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 metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and reinforces its overall durability,
• Magnets lose power 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. If exposed to rain, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing complex structures directly in the magnet,
• Potential hazard from tiny pieces may arise, in case of ingestion, which is notable in the protection of children. It should also be noted that tiny components from these devices have the potential to hinder health screening after being swallowed,
• In cases of tight budgets, neodymium magnet cost is a challenge,

Best holding force of the magnet in ideal parameters – what it depends on?

The given pulling force of the magnet means the maximum force, calculated in ideal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

Determinants of lifting force in real conditions

Practical lifting force is determined by elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, because 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 using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.