SM 25x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their strength remains stable, and after approximately ten years it drops only by ~1% (theoretically),
• They do not lose their magnetic properties even under external field action,
• The use of an shiny finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnetic induction on the working part of the magnet is impressive,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to freedom in shaping and the ability to customize to complex applications,
• Versatile presence in high-tech industry – they are utilized in hard drives, motor assemblies, advanced medical instruments, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which makes them useful in compact constructions

Cons of neodymium magnets: weaknesses and usage proposals

• At strong impacts they can break, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and 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
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited possibility of making nuts in the magnet and complicated forms - recommended is a housing - mounting mechanism.
• Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which becomes key in the context of child health protection. Furthermore, small components 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

Breakaway strength of the magnet in ideal conditions – what affects it?

The declared magnet strength represents the peak performance, obtained under laboratory conditions, specifically:

• on a block made of structural steel, optimally conducting the magnetic field
• whose thickness is min. 10 mm
• with a surface free of scratches
• with zero gap (without coatings)
• under perpendicular force vector (90-degree angle)
• in stable room temperature

Magnet lifting force in use – key factors

In practice, the actual lifting capacity depends on several key aspects, presented from the most important:

• Gap between surfaces – even a fraction of a millimeter of distance (caused e.g. by veneer or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Steel thickness – too thin plate does not accept the full field, causing part of the flux to be wasted to the other side.
• Metal type – different alloys attracts identically. High carbon content weaken the attraction effect.
• Surface finish – full contact is obtained only on polished steel. Any scratches and bumps create air cushions, reducing force.
• Operating temperature – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate reduces the holding force.