SMZR 25x225 / N52 - magnetic separator with handle

Pros as well as cons of neodymium magnets.

Apart from their notable magnetism, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• They have excellent resistance to weakening of magnetic properties when exposed to external fields,
• In other words, due to the metallic layer of gold, the element is aesthetically pleasing,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures approaching 230°C and above...
• Thanks to freedom in constructing and the capacity to customize to complex applications,
• Wide application in modern industrial fields – they find application in mass storage devices, drive modules, medical devices, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in miniature devices

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can break, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's 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 very resistant to heat
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• Limited ability of making threads in the magnet and complex shapes - preferred is a housing - mounting mechanism.
• Health risk resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child safety. Additionally, tiny parts of these products can complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what it depends on?

Breakaway force was determined for ideal contact conditions, assuming:

• on a base made of structural steel, optimally conducting the magnetic field
• with a thickness minimum 10 mm
• characterized by lack of roughness
• without the slightest insulating layer between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Please note that the magnet holding may be lower influenced by the following factors, starting with the most relevant:

• Clearance – the presence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is available only during perpendicular pulling. The force required to slide of the magnet along the surface is usually many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Material composition – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
• Surface quality – the more even the plate, the larger the contact zone and higher the lifting capacity. Roughness creates an air distance.
• Thermal environment – temperature increase causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the holding force.