MW 15x4 / N38 - cylindrical magnet

Strengths and weaknesses of neodymium magnets.

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

• They retain full power for around 10 years – the loss is just ~1% (in theory),
• Magnets perfectly protect themselves against loss of magnetization caused by foreign field sources,
• Thanks to the metallic finish, the coating of nickel, gold, or silver gives an aesthetic appearance,
• Magnetic induction on the top side of the magnet turns out to be extremely intense,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to modularity in shaping and the ability to adapt to complex applications,
• Universal use in modern technologies – they serve a role in magnetic memories, motor assemblies, advanced medical instruments, also technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets decrease their strength 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 durability even at temperatures 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 magnets in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest a housing - magnetic mount, due to difficulties in creating nuts inside the magnet and complex forms.
• Possible danger resulting from small fragments of magnets can be dangerous, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small components of these devices can disrupt the diagnostic process medical after entering the body.
• With large orders the cost of neodymium magnets is a challenge,

Maximum lifting capacity of the magnet – what affects it?

The load parameter shown concerns the maximum value, measured under laboratory conditions, specifically:

• using a sheet made of high-permeability steel, acting as a magnetic yoke
• possessing a massiveness of min. 10 mm to avoid saturation
• with a plane free of scratches
• with direct contact (no impurities)
• during detachment in a direction perpendicular to the mounting surface
• at temperature room level

Practical aspects of lifting capacity – factors

In real-world applications, the actual holding force is determined by a number of factors, ranked from the most important:

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds significantly lower power (typically approx. 20-30% of maximum force).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel gives the best results. Alloy admixtures lower magnetic permeability and holding force.
• Smoothness – full contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Temperature – heating the magnet causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.