MW 10x10 / N38 - cylindrical magnet

Strengths as well as weaknesses of NdFeB magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over around 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They show high resistance to demagnetization induced by external magnetic fields,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to present itself better,
• The surface of neodymium magnets generates a unique magnetic field – this is a distinguishing feature,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to versatility in forming and the capacity to modify to individual projects,
• Key role in electronics industry – they are utilized in mass storage devices, motor assemblies, advanced medical instruments, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

What to avoid - cons of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a strong case, which not only protects them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power 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. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• Limited possibility of making threads in the magnet and complicated shapes - recommended is cover - mounting mechanism.
• Health risk resulting from small fragments of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. It is also worth noting that small elements of these devices are able to be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum lifting force for a neodymium magnet – what contributes to it?

The declared magnet strength refers to the limit force, obtained under laboratory conditions, namely:

• with the application of a yoke made of special test steel, ensuring maximum field concentration
• with a cross-section no less than 10 mm
• characterized by even structure
• with direct contact (no impurities)
• during detachment in a direction vertical to the mounting surface
• in temp. approx. 20°C

Practical lifting capacity: influencing factors

Bear in mind that the application force will differ depending on elements below, starting with the most relevant:

• Gap (betwixt the magnet and the plate), since even a very small clearance (e.g. 0.5 mm) can cause a decrease in force by up to 50% (this also applies to varnish, rust or dirt).
• Loading method – catalog parameter refers to detachment vertically. When applying parallel force, the magnet holds much less (often approx. 20-30% of nominal force).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material composition – different alloys attracts identically. Alloy additives weaken the attraction effect.
• Base smoothness – the more even the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal factor – high temperature weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

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