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

Advantages as well as disadvantages of NdFeB magnets.

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

• They have constant strength, and over more than ten years their attraction force decreases symbolically – ~1% (in testing),
• They maintain their magnetic properties even under external field action,
• Thanks to the shiny finish, the coating of Ni-Cu-Ni, gold, or silver gives an modern appearance,
• Neodymium magnets create maximum magnetic induction on a small area, which allows for strong attraction,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of exact machining and modifying to individual applications,
• Universal use in innovative solutions – they serve a role in data components, electromotive mechanisms, medical equipment, and industrial machines.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

What to avoid - cons of neodymium magnets: application proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (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
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Limited ability of making threads in the magnet and complex forms - preferred is cover - mounting mechanism.
• Possible danger related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these magnets 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

Magnetic strength at its maximum – what contributes to it?

The lifting capacity listed is a measurement result conducted under specific, ideal conditions:

• on a plate made of structural steel, optimally conducting the magnetic flux
• whose transverse dimension reaches at least 10 mm
• characterized by lack of roughness
• with zero gap (no coatings)
• during pulling in a direction perpendicular to the mounting surface
• in temp. approx. 20°C

Key elements affecting lifting force

Effective lifting capacity impacted by working environment parameters, mainly (from most important):

• Clearance – existence of any layer (rust, dirt, air) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is standardly several times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of converting into lifting capacity.
• Material type – the best choice is pure iron steel. Stainless steels may attract less.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment weakens pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity was measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.