SM 32x425 [2xM8] / N42 - magnetic separator

Pros and cons of rare earth magnets.

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

• They do not lose magnetism, even during nearly 10 years – the decrease in strength is only ~1% (theoretically),
• Neodymium magnets are characterized by extremely resistant to demagnetization caused by magnetic disturbances,
• In other words, due to the metallic layer of gold, the element gains a professional look,
• Magnetic induction on the top side of the magnet turns out to be strong,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate shaping and optimizing to specific applications,
• Wide application in high-tech industry – they serve a role in hard drives, motor assemblies, precision medical tools, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which enables their usage in compact constructions

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• 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 protects them against impacts but also raises their durability
• NdFeB magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of creating threads in the magnet and complex shapes - preferred is a housing - mounting mechanism.
• Health risk related to microscopic parts of magnets are risky, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small elements of these devices can be problematic in diagnostics medical in case of swallowing.
• With mass production the cost of neodymium magnets is economically unviable,

Best holding force of the magnet in ideal parameters – what affects it?

The load parameter shown concerns the peak performance, measured under optimal environment, specifically:

• on a base made of mild steel, optimally conducting the magnetic field
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• characterized by even structure
• without the slightest air gap between the magnet and steel
• under vertical force vector (90-degree angle)
• in neutral thermal conditions

Key elements affecting lifting force

In real-world applications, the real power depends on many variables, listed from crucial:

• Air gap (between the magnet and the metal), because even a very small clearance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Force direction – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – mild steel attracts best. Higher carbon content reduce magnetic permeability and lifting capacity.
• Surface condition – ground elements ensure maximum contact, which improves force. Rough surfaces reduce efficiency.
• Heat – 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 carried out on a smooth plate of optimal thickness, under perpendicular forces, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.