SM 25x350 [2xM8] / N52 - magnetic separator

Pros and cons of rare earth magnets.

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

• They have stable power, and over nearly 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They possess excellent resistance to magnetism drop when exposed to external fields,
• A magnet with a smooth nickel surface has an effective appearance,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures reaching 230°C and above...
• Thanks to freedom in forming and the capacity to modify to complex applications,
• Huge importance in advanced technology sectors – they are used in data components, electromotive mechanisms, diagnostic systems, and technologically advanced constructions.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only protects the magnet but also increases its resistance to damage
• Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Limited ability of producing threads in the magnet and complicated shapes - preferred is casing - magnetic holder.
• Possible danger resulting from small fragments of magnets pose a threat, if swallowed, which gains importance in the context of child health protection. It is also worth noting that tiny parts of these products can complicate diagnosis medical after entering the body.
• With mass production the cost of neodymium magnets is economically unviable,

Maximum lifting force for a neodymium magnet – what it depends on?

Holding force of 0 kg is a measurement result executed under specific, ideal conditions:

• with the use of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• possessing a thickness of minimum 10 mm to avoid saturation
• with an ground contact surface
• without the slightest air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at temperature room level

Lifting capacity in practice – influencing factors

Please note that the application force may be lower depending on elements below, starting with the most relevant:

• Clearance – existence of any layer (rust, tape, gap) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is obtained only during perpendicular pulling. The shear force of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of generating force.
• Plate material – mild steel gives the best results. Alloy steels reduce magnetic properties and lifting capacity.
• Smoothness – ideal contact is possible only on polished steel. Rough texture reduce the real contact area, reducing force.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, however under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the lifting capacity.