SM 25x275 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

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

• They do not lose strength, even during around ten years – the drop in strength is only ~1% (theoretically),
• They are noted for resistance to demagnetization induced by external magnetic fields,
• Thanks to the glossy finish, the surface of Ni-Cu-Ni, gold-plated, or silver-plated gives an aesthetic appearance,
• Neodymium magnets deliver maximum magnetic induction on a their surface, which increases force concentration,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to the potential of precise forming and customization to specialized needs, magnetic components can be manufactured in a broad palette of shapes and sizes, which expands the range of possible applications,
• Versatile presence in future technologies – they are commonly used in magnetic memories, electromotive mechanisms, medical equipment, as well as technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in small systems

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we suggest using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (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
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in creating threads and complex forms in magnets, we propose using a housing - magnetic mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. It is also worth noting that tiny parts of these magnets can disrupt the diagnostic process medical when they are in the body.
• With mass production the cost of neodymium magnets can be a barrier,

Detachment force of the magnet in optimal conditions – what it depends on?

The specified lifting capacity concerns the limit force, recorded under laboratory conditions, meaning:

• using a plate made of mild steel, acting as a circuit closing element
• with a thickness no less than 10 mm
• characterized by even structure
• with direct contact (without paint)
• for force acting at a right angle (in the magnet axis)
• in neutral thermal conditions

Determinants of lifting force in real conditions

In practice, the actual lifting capacity is determined by a number of factors, listed from most significant:

• Space between magnet and steel – every millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – too thin sheet does not close the flux, causing part of the power to be wasted into the air.
• Steel grade – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
• Plate texture – smooth surfaces guarantee perfect abutment, which improves field saturation. Uneven metal reduce efficiency.
• Temperature influence – hot environment weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet and the plate decreases the holding force.