MP 14x8/4x3 / N38 - ring magnet

Strengths and weaknesses of rare earth magnets.

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

• They have constant strength, and over nearly ten years their attraction force decreases symbolically – ~1% (in testing),
• They maintain their magnetic properties even under strong external field,
• In other words, due to the reflective layer of gold, the element looks attractive,
• 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 shape) even at temperatures up to 230°C and higher...
• Thanks to freedom in designing and the ability to customize to individual projects,
• Significant place in modern industrial fields – they are utilized in hard drives, motor assemblies, diagnostic systems, also other advanced devices.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Problematic aspects of neodymium magnets: tips and applications.

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop 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 start to 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.
• Due to limitations in producing threads and complex shapes in magnets, we propose using casing - magnetic holder.
• Health risk to health – tiny shards of magnets can be dangerous, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these devices can disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum magnetic pulling force – what affects it?

The lifting capacity listed is a measurement result performed under standard conditions:

• using a plate made of high-permeability steel, acting as a ideal flux conductor
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a plane cleaned and smooth
• with direct contact (no impurities)
• under perpendicular force direction (90-degree angle)
• at room temperature

Key elements affecting lifting force

Bear in mind that the magnet holding will differ subject to elements below, starting with the most relevant:

• Clearance – the presence of foreign body (paint, dirt, air) acts as an insulator, which reduces power steeply (even by 50% at 0.5 mm).
• Force direction – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the maximum value.
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material type – the best choice is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Base smoothness – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Temperature – temperature increase causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate decreases the lifting capacity.