UMH 25x8x45 [M5] / N38 - magnetic holder with hook

Pros and cons of neodymium magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain full power for nearly 10 years – the loss is just ~1% (in theory),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• Thanks to the elegant finish, the layer of Ni-Cu-Ni, gold-plated, or silver-plated gives an visually attractive appearance,
• Magnets are distinguished by huge magnetic induction on the active area,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of exact modeling and modifying to individual applications,
• Significant place in innovative solutions – they find application in computer drives, brushless drives, precision medical tools, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which allows their use in compact constructions

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks under impact, we suggest using special steel holders. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening 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
• They oxidize in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of producing nuts in the magnet and complex shapes - recommended is casing - magnetic holder.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which gains importance in the context of child health protection. Furthermore, tiny parts of these products are able to disrupt the diagnostic process medical after entering the body.
• With mass production the cost of neodymium magnets is economically unviable,

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

The specified lifting capacity refers to the limit force, measured under laboratory conditions, namely:

• on a block made of mild steel, perfectly concentrating the magnetic field
• whose thickness equals approx. 10 mm
• with a plane free of scratches
• under conditions of no distance (metal-to-metal)
• during pulling in a direction vertical to the plane
• in stable room temperature

Magnet lifting force in use – key factors

Bear in mind that the working load may be lower depending on the following factors, starting with the most relevant:

• Gap between surfaces – every millimeter of separation (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of maximum force).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material type – the best choice is pure iron steel. Cast iron may have worse magnetic properties.
• Plate texture – smooth surfaces guarantee perfect abutment, which increases field saturation. Uneven metal reduce efficiency.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, however under shearing force the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.