SM 32x200 [2xM8] / N52 - magnetic separator

Pros as well as cons of rare earth magnets.

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

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• They are noted for resistance to demagnetization induced by presence of other magnetic fields,
• In other words, due to the metallic finish of gold, the element gains visual value,
• Magnetic induction on the working layer of the magnet is maximum,
• Thanks to resistance to high temperature, they are capable of working (depending on the form) even at temperatures up to 230°C and higher...
• Due to the potential of free molding and adaptation to individualized solutions, NdFeB magnets can be manufactured in a broad palette of geometric configurations, which makes them more universal,
• Universal use in high-tech industry – they find application in magnetic memories, brushless drives, diagnostic systems, and technologically advanced constructions.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• To avoid cracks under impact, we suggest using special steel holders. Such a solution secures the magnet and simultaneously increases its durability.
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening 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
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We suggest casing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complex forms.
• Health risk to health – tiny shards of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small components of these magnets are able to be problematic in diagnostics medical when they are in 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 contributes to it?

The force parameter is a measurement result executed under standard conditions:

• on a block made of mild steel, perfectly concentrating the magnetic field
• whose transverse dimension equals approx. 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• under axial application of breakaway force (90-degree angle)
• at room temperature

Determinants of practical lifting force of a magnet

Real force is affected by working environment parameters, mainly (from most important):

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material composition – different alloys attracts identically. High carbon content weaken the interaction with the magnet.
• Surface quality – the more even the surface, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, however under shearing force the load capacity is reduced by as much as 5 times. In addition, even a slight gap {between} the magnet and the plate decreases the holding force.