MW 55x25 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

Besides their immense strength, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• Magnets perfectly protect themselves against loss of magnetization caused by ambient magnetic noise,
• A magnet with a metallic silver surface has better aesthetics,
• The surface of neodymium magnets generates a intense magnetic field – this is one of their assets,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to versatility in forming and the capacity to modify to unusual requirements,
• Key role in modern technologies – they are utilized in computer drives, electromotive mechanisms, advanced medical instruments, also other advanced devices.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• At very strong impacts they can break, therefore we advise placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (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
• They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating nuts and complex shapes in magnets, we recommend using a housing - magnetic mount.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. Furthermore, small elements of these devices are able to complicate diagnosis medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Detachment force of the magnet in optimal conditions – what contributes to it?

Breakaway force was determined for ideal contact conditions, including:

• with the use of a sheet made of special test steel, ensuring full magnetic saturation
• whose transverse dimension is min. 10 mm
• with an ground contact surface
• with total lack of distance (no coatings)
• under perpendicular force vector (90-degree angle)
• in temp. approx. 20°C

Lifting capacity in practice – influencing factors

Holding efficiency is affected by specific conditions, including (from most important):

• Gap (betwixt the magnet and the plate), as even a tiny distance (e.g. 0.5 mm) leads to a reduction in force by up to 50% (this also applies to paint, corrosion or dirt).
• Load vector – maximum parameter is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of generating force.
• Material composition – not every steel attracts identically. Alloy additives weaken the attraction effect.
• Base smoothness – the more even the plate, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.