MW 2x4 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

Apart from their superior magnetic energy, neodymium magnets have these key benefits:

• They retain attractive force for around ten years – the drop is just ~1% (according to analyses),
• Magnets effectively resist against demagnetization caused by ambient magnetic noise,
• By covering with a lustrous coating of silver, the element presents an elegant look,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures reaching 230°C and above...
• Considering the option of flexible shaping and adaptation to individualized solutions, magnetic components can be created in a broad palette of shapes and sizes, which amplifies use scope,
• Universal use in electronics industry – they serve a role in magnetic memories, electric drive systems, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in small systems

Disadvantages of NdFeB magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a strong case, which not only secures them against impacts but also raises their durability
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• Due to limitations in realizing threads and complicated shapes in magnets, we propose using cover - magnetic mount.
• Possible danger resulting from small fragments of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. It is also worth noting that small elements of these devices can be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is higher than average,

Best holding force of the magnet in ideal parameters – what contributes to it?

The force parameter is a result of laboratory testing conducted under specific, ideal conditions:

• on a plate made of structural steel, perfectly concentrating the magnetic flux
• possessing a thickness of min. 10 mm to ensure full flux closure
• with an ideally smooth touching surface
• without the slightest insulating layer between the magnet and steel
• under vertical force vector (90-degree angle)
• at ambient temperature room level

Determinants of lifting force in real conditions

Effective lifting capacity impacted by specific conditions, mainly (from priority):

• Air gap (betwixt the magnet and the metal), as even a very small clearance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or dirt).
• Loading method – declared lifting capacity refers to detachment vertically. When slipping, the magnet exhibits much less (typically approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material type – ideal substrate is high-permeability steel. Cast iron may attract less.
• Surface finish – ideal contact is obtained only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.