SM 32x275 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even during around ten years – the drop in power is only ~1% (according to tests),
• They feature excellent resistance to magnetism drop as a result of opposing magnetic fields,
• A magnet with a metallic nickel surface has an effective appearance,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to versatility in constructing and the capacity to modify to specific needs,
• Wide application in electronics industry – they find application in computer drives, motor assemblies, diagnostic systems, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which enables their usage in compact constructions

Cons of neodymium magnets: tips and applications.

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• Neodymium magnets decrease their power 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
• They rust in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mount, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Potential hazard to health – tiny shards of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these devices can disrupt the diagnostic process medical after entering the body.
• With budget limitations the cost of neodymium magnets is a challenge,

Maximum holding power of the magnet – what contributes to it?

The force parameter is a theoretical maximum value executed under specific, ideal conditions:

• on a plate made of mild steel, perfectly concentrating the magnetic flux
• whose thickness equals approx. 10 mm
• with an polished touching surface
• under conditions of gap-free contact (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at room temperature

Key elements affecting lifting force

During everyday use, the actual lifting capacity depends on several key aspects, ranked from most significant:

• Space between surfaces – every millimeter of distance (caused e.g. by varnish or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Force direction – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of generating force.
• Material type – ideal substrate is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface condition – ground elements ensure maximum contact, which increases field saturation. Rough surfaces reduce efficiency.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, however under shearing force the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate lowers the holding force.