MP 60x20x5 / N38 - ring magnet

Advantages and disadvantages of rare earth magnets.

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

• They do not lose magnetism, even over approximately 10 years – the reduction in strength is only ~1% (according to tests),
• Neodymium magnets prove to be highly resistant to demagnetization caused by external interference,
• Thanks to the shimmering finish, the plating of Ni-Cu-Ni, gold, or silver-plated gives an visually attractive appearance,
• Neodymium magnets achieve maximum magnetic induction on a their surface, which increases force concentration,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to versatility in constructing and the capacity to adapt to client solutions,
• Key role in future technologies – they are commonly used in magnetic memories, electric motors, diagnostic systems, and other advanced devices.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also improves its resistance to damage
• Neodymium magnets decrease their force 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 stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Limited ability of producing nuts in the magnet and complex forms - preferred is casing - mounting mechanism.
• Possible danger to health – tiny shards of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small components of these products are able to complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum holding power of the magnet – what it depends on?

The load parameter shown refers to the limit force, obtained under laboratory conditions, namely:

• with the contact of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• possessing a thickness of minimum 10 mm to avoid saturation
• characterized by lack of roughness
• with zero gap (without impurities)
• during pulling in a direction perpendicular to the mounting surface
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

Bear in mind that the working load may be lower influenced by elements below, in order of importance:

• Gap between magnet and steel – every millimeter of separation (caused e.g. by varnish or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When slipping, the magnet holds much less (typically approx. 20-30% of nominal force).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Plate material – mild steel gives the best results. Higher carbon content lower magnetic permeability and holding force.
• Plate texture – ground elements ensure maximum contact, which improves field saturation. Rough surfaces reduce efficiency.
• Heat – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost gain strength (up to a certain limit).

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.