SM 25x175 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

Besides their tremendous pulling force, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after 10 years the performance loss is only ~1% (in laboratory conditions),
• They retain their magnetic properties even under close interference source,
• A magnet with a smooth nickel surface has better aesthetics,
• The surface of neodymium magnets generates a unique magnetic field – this is a key feature,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to modularity in forming and the ability to customize to individual projects,
• Wide application in modern industrial fields – they are utilized in HDD drives, brushless drives, diagnostic systems, and technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Characteristics of disadvantages of neodymium magnets: weaknesses and usage proposals

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a steel housing, which not only protects them against impacts but also increases their durability
• Neodymium magnets decrease their force 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 durability even at temperatures up to 230°C
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing threads and complicated forms in magnets, we propose using a housing - magnetic mechanism.
• Health risk related to microscopic parts of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small components of these devices can be problematic in diagnostics medical after entering the body.
• With large orders the cost of neodymium magnets is a challenge,

Detachment force of the magnet in optimal conditions – what contributes to it?

Magnet power was determined for ideal contact conditions, taking into account:

• with the contact of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• whose transverse dimension is min. 10 mm
• characterized by even structure
• without the slightest insulating layer between the magnet and steel
• under vertical force vector (90-degree angle)
• at room temperature

Magnet lifting force in use – key factors

In practice, the actual lifting capacity depends on many variables, ranked from the most important:

• 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.
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material type – the best choice is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Thermal conditions – neodymium magnets have a sensitivity to temperature. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, whereas under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet and the plate reduces the load capacity.