MW 28.9x10 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their strength is maintained, and after approximately ten years it drops only by ~1% (according to research),
• Neodymium magnets are highly resistant to loss of magnetic properties caused by external field sources,
• A magnet with a shiny nickel surface has better aesthetics,
• Magnetic induction on the surface of the magnet turns out to be very high,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Thanks to the potential of free forming and customization to individualized projects, neodymium magnets can be manufactured in a wide range of geometric configurations, which makes them more universal,
• Universal use in modern technologies – they are commonly used in data components, motor assemblies, medical equipment, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which enables their usage in small systems

Disadvantages of neodymium magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• Limited ability of making nuts in the magnet and complex forms - recommended is casing - mounting mechanism.
• Possible danger resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the context of child safety. Furthermore, small components of these devices can disrupt the diagnostic process medical in case of swallowing.
• 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 capacity of the magnet – what contributes to it?

Breakaway force was defined for optimal configuration, including:

• with the contact of a sheet made of low-carbon steel, ensuring maximum field concentration
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• with total lack of distance (no impurities)
• during pulling in a direction perpendicular to the plane
• at temperature room level

Lifting capacity in real conditions – factors

Please note that the application force may be lower influenced by the following factors, starting with the most relevant:

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Load vector – highest force is obtained only during perpendicular pulling. The resistance to sliding of the magnet along the plate is typically several times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Smoothness – ideal contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.