SM 25x400 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

Besides their tremendous field intensity, neodymium magnets offer the following advantages:

• They have constant strength, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets remain remarkably resistant to loss of magnetic properties caused by external interference,
• The use of an shiny layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnetic induction on the working layer of the magnet remains exceptional,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Considering the potential of flexible molding and customization to unique requirements, NdFeB magnets can be modeled in a wide range of shapes and sizes, which makes them more universal,
• Huge importance in future technologies – they are utilized in data components, electric drive systems, diagnostic systems, as well as other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in compact constructions

Problematic aspects of neodymium magnets: application proposals

• To avoid cracks under impact, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can reduce their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• Limited ability of making threads in the magnet and complex forms - recommended is casing - magnet mounting.
• Potential hazard related to microscopic parts of magnets pose a threat, in case of ingestion, which becomes key in the context of child safety. Furthermore, small elements of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what affects it?

The load parameter shown represents the peak performance, obtained under laboratory conditions, meaning:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a surface cleaned and smooth
• without the slightest insulating layer between the magnet and steel
• under axial force direction (90-degree angle)
• at ambient temperature room level

Lifting capacity in practice – influencing factors

Bear in mind that the application force will differ subject to the following factors, starting with the most relevant:

• Air gap (between the magnet and the plate), since even a tiny distance (e.g. 0.5 mm) results in a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Force direction – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet exhibits much less (typically approx. 20-30% of maximum force).
• Steel thickness – too thin plate causes magnetic saturation, causing part of the power to be wasted to the other side.
• Material type – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
• Surface quality – the more even the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal environment – temperature increase causes a temporary drop of induction. Check the thermal limit for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.