MW 20x5 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over more than 10 years their performance decreases symbolically – ~1% (according to theory),
• Neodymium magnets prove to be highly resistant to loss of magnetic properties caused by external field sources,
• Thanks to the reflective finish, the coating of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• Magnets are characterized by huge magnetic induction on the outer side,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in forming and the capacity to adapt to unusual requirements,
• Significant place in modern technologies – they are used in data components, electromotive mechanisms, advanced medical instruments, and multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which allows their use in small systems

Problematic aspects of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited ability of making threads in the magnet and complicated shapes - recommended is cover - magnet mounting.
• Possible danger related to microscopic parts of magnets are risky, if swallowed, which becomes key in the context of child health protection. It is also worth noting that small elements of these magnets are able to disrupt the diagnostic process medical in case of swallowing.
• With budget limitations the cost of neodymium magnets can be a barrier,

Maximum lifting force for a neodymium magnet – what it depends on?

The load parameter shown refers to the limit force, obtained under optimal environment, namely:

• using a base made of low-carbon steel, serving as a ideal flux conductor
• whose transverse dimension reaches at least 10 mm
• with a plane perfectly flat
• with direct contact (no impurities)
• for force acting at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Practical lifting capacity: influencing factors

Please note that the working load may be lower subject to the following factors, in order of importance:

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of maximum 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 composition – different alloys reacts the same. High carbon content worsen the interaction with the magnet.
• Surface quality – the more even the surface, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.