MW 100x30 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets.

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

• They do not lose magnetism, even over around 10 years – the drop in power is only ~1% (based on measurements),
• They are extremely resistant to demagnetization induced by external disturbances,
• A magnet with a metallic silver surface has better aesthetics,
• Magnetic induction on the surface of the magnet remains maximum,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to the potential of precise shaping and adaptation to unique needs, neodymium magnets can be modeled in a variety of shapes and sizes, which amplifies use scope,
• Significant place in modern industrial fields – they serve a role in hard drives, electric drive systems, medical devices, also industrial machines.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a special holder, which not only protects them against impacts but also increases their durability
• Neodymium magnets lose power when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• 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 as well as corrosion.
• We suggest cover - magnetic mount, due to difficulties in producing nuts inside the magnet and complex shapes.
• Health risk related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these products are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum lifting force for a neodymium magnet – what affects it?

The specified lifting capacity refers to the peak performance, obtained under optimal environment, specifically:

• using a plate made of mild steel, serving as a magnetic yoke
• whose thickness reaches at least 10 mm
• with a plane free of scratches
• without any air gap between the magnet and steel
• under perpendicular force vector (90-degree angle)
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

Holding efficiency is influenced by working environment parameters, including (from priority):

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Base massiveness – too thin steel does not accept the full field, causing part of the flux to be escaped to the other side.
• Chemical composition of the base – low-carbon steel gives the best results. Higher carbon content reduce magnetic properties and holding force.
• Plate texture – ground elements guarantee perfect abutment, which increases field saturation. Uneven metal weaken the grip.
• Temperature influence – hot environment weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate reduces the load capacity.