UMH 75x18x68 [M8] / N38 - magnetic holder with hook

Strengths and weaknesses of neodymium magnets.

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

• They have constant strength, and over nearly ten years their performance decreases symbolically – ~1% (in testing),
• They retain their magnetic properties even under external field action,
• Thanks to the shimmering finish, the coating of nickel, gold, or silver gives an professional appearance,
• The surface of neodymium magnets generates a concentrated magnetic field – this is a distinguishing feature,
• 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 freedom in constructing and the capacity to customize to unusual requirements,
• Wide application in high-tech industry – they are utilized in HDD drives, brushless drives, medical devices, as well as industrial machines.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We recommend casing - magnetic mount, due to difficulties in realizing nuts inside the magnet and complex shapes.
• Health risk to health – tiny shards of magnets are risky, if swallowed, which gains importance in the context of child safety. Furthermore, small elements of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets is a challenge,

Highest magnetic holding force – what contributes to it?

Holding force of 162 kg is a result of laboratory testing executed under standard conditions:

• on a base made of structural steel, perfectly concentrating the magnetic field
• possessing a massiveness of at least 10 mm to ensure full flux closure
• with a plane free of scratches
• with total lack of distance (without impurities)
• during detachment in a direction perpendicular to the mounting surface
• at room temperature

Determinants of lifting force in real conditions

Real force impacted by specific conditions, such as (from priority):

• Space between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet holds much less (often approx. 20-30% of maximum force).
• Base massiveness – insufficiently thick plate causes magnetic saturation, causing part of the flux to be lost into the air.
• Plate material – mild steel gives the best results. Alloy steels lower magnetic permeability and lifting capacity.
• Smoothness – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.