SM 25x125 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They retain their attractive force for around 10 years – the loss is just ~1% (in theory),
• They are very resistant to demagnetization caused by external magnetic fields,
• By applying a bright layer of gold, the element gains a modern 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,
• Thanks to the possibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their application range,
• Wide application in advanced technical fields – they serve a purpose in data storage devices, rotating machines, diagnostic apparatus along with technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which allows for use in small systems

Disadvantages of magnetic elements:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall resistance,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of rubber for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the challenges in manufacturing holes directly in the magnet,
• Possible threat related to magnet particles may arise, if ingested accidentally, which is crucial in the protection of children. Additionally, tiny components from these products have the potential to disrupt scanning after being swallowed,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

Highest magnetic holding force – what affects it?

The given pulling force of the magnet means the maximum force, determined under optimal conditions, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Determinants of lifting force in real conditions

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) 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 measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the holding force.