MP 62x42x25 / N38 - ring magnet

Strengths as well as weaknesses of NdFeB magnets.

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

• They retain full power for around 10 years – the drop is just ~1% (in theory),
• They are extremely resistant to demagnetization induced by external magnetic fields,
• The use of an aesthetic coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Magnets are characterized by maximum magnetic induction on the outer layer,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures approaching 230°C and above...
• Thanks to versatility in forming and the capacity to adapt to individual projects,
• Huge importance in high-tech industry – they are used in magnetic memories, brushless drives, advanced medical instruments, and technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Cons of neodymium magnets and ways of using them

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• Limited possibility of producing threads in the magnet and complicated forms - preferred is a housing - mounting mechanism.
• Health risk to health – tiny shards of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child safety. It is also worth noting that small components of these magnets are able to complicate diagnosis medical after entering the body.
• With mass production the cost of neodymium magnets can be a barrier,

Detachment force of the magnet in optimal conditions – what contributes to it?

The lifting capacity listed is a result of laboratory testing performed under specific, ideal conditions:

• with the use of a sheet made of special test steel, ensuring full magnetic saturation
• with a thickness of at least 10 mm
• characterized by lack of roughness
• with zero gap (without coatings)
• under axial force vector (90-degree angle)
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

In practice, the actual holding force depends on a number of factors, presented from most significant:

• Gap (betwixt the magnet and the plate), since even a tiny clearance (e.g. 0.5 mm) leads to a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
• Angle of force application – 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 smaller (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Steel grade – the best choice is pure iron steel. Cast iron may attract less.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Operating temperature – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under perpendicular forces, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a small distance {between} the magnet and the plate decreases the holding force.