SM 25x350 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of NdFeB magnets.

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

• They have stable power, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets are characterized by highly resistant to demagnetization caused by external field sources,
• Thanks to the shiny finish, the layer of nickel, gold-plated, or silver gives an visually attractive appearance,
• Magnets are distinguished by extremely high magnetic induction on the outer layer,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling action at temperatures approaching 230°C and above...
• Thanks to modularity in shaping and the ability to customize to unusual requirements,
• Huge importance in future technologies – they are used in computer drives, brushless drives, precision medical tools, also industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's 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
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• We suggest cover - magnetic holder, due to difficulties in realizing threads inside the magnet and complex shapes.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small elements of these products are able to 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 refers to the peak performance, measured under ideal test conditions, namely:

• on a block made of structural steel, perfectly concentrating the magnetic field
• possessing a thickness of min. 10 mm to ensure full flux closure
• characterized by smoothness
• under conditions of no distance (surface-to-surface)
• under axial application of breakaway force (90-degree angle)
• at conditions approx. 20°C

Magnet lifting force in use – key factors

During everyday use, the real power is determined by several key aspects, ranked from most significant:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When slipping, the magnet holds much less (often approx. 20-30% of nominal force).
• Base massiveness – insufficiently thick steel does not close the flux, causing part of the flux to be wasted to the other side.
• Steel type – low-carbon steel gives the best results. Alloy admixtures reduce magnetic permeability and holding force.
• Surface structure – the more even the plate, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Temperature – temperature increase results in weakening of induction. Check the maximum operating temperature for a given model.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.