SMZR 32x125 / N52 - magnetic separator with handle

Strengths as well as weaknesses of rare earth magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (based on calculations),
• They feature excellent resistance to magnetic field loss due to external magnetic sources,
• Thanks to the metallic finish, the plating of nickel, gold, or silver-plated gives an visually attractive appearance,
• Magnetic induction on the working layer of the magnet remains strong,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, enabling functioning at temperatures approaching 230°C and above...
• Thanks to versatility in forming and the capacity to adapt to complex applications,
• Fundamental importance in modern industrial fields – they are commonly used in mass storage devices, brushless drives, diagnostic systems, and industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited possibility of producing nuts in the magnet and complicated forms - recommended is a housing - magnet mounting.
• Potential hazard resulting from small fragments of magnets are risky, if swallowed, which gains importance in the aspect of protecting the youngest. Additionally, small elements of these products can complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is economically unviable,

Maximum lifting capacity of the magnet – what it depends on?

Information about lifting capacity is the result of a measurement for optimal configuration, assuming:

• on a block made of mild steel, perfectly concentrating the magnetic flux
• possessing a massiveness of at least 10 mm to ensure full flux closure
• with a plane perfectly flat
• without any air gap between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

In practice, the real power results from a number of factors, listed from the most important:

• Distance – existence of any layer (rust, dirt, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the flux to be escaped into the air.
• Metal type – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases field saturation. Uneven metal weaken the grip.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, however under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.