SM 19x225 [2xM6] / N50 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

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

• They have constant strength, and over more than ten years their attraction force decreases symbolically – ~1% (according to theory),
• They do not lose their magnetic properties even under close interference source,
• A magnet with a smooth gold surface has better aesthetics,
• They show high magnetic induction at the operating surface, making them more effective,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in shaping and the ability to modify to specific needs,
• Wide application in future technologies – they are utilized in mass storage devices, electric motors, medical devices, also complex engineering applications.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of creating threads in the magnet and complicated forms - recommended is a housing - magnet mounting.
• Health risk resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, tiny parts of these devices are able to disrupt the diagnostic process medical when they are in the body.
• With budget limitations the cost of neodymium magnets can be a barrier,

Maximum magnetic pulling force – what it depends on?

The declared magnet strength refers to the limit force, measured under laboratory conditions, specifically:

• with the use of a sheet made of low-carbon steel, ensuring maximum field concentration
• possessing a thickness of minimum 10 mm to avoid saturation
• with a surface perfectly flat
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction vertical to the plane
• at conditions approx. 20°C

Lifting capacity in practice – influencing factors

In practice, the real power is determined by several key aspects, ranked from crucial:

• Space between magnet and steel – every millimeter of separation (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet exhibits much less (often approx. 20-30% of maximum force).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Steel type – mild steel gives the best results. Alloy steels reduce magnetic properties and lifting capacity.
• Surface finish – ideal contact is obtained only on polished steel. Rough texture create air cushions, weakening the magnet.
• Operating temperature – NdFeB sinters have a negative temperature coefficient. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

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