UMH 60x15x69 [M8] / N38 - magnetic holder with hook

Strengths as well as weaknesses of rare earth magnets.

Apart from their strong holding force, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after 10 years the performance loss is only ~1% (according to literature),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• Thanks to the smooth finish, the coating of Ni-Cu-Ni, gold, or silver-plated gives an elegant appearance,
• Magnetic induction on the working layer of the magnet is very high,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to freedom in forming and the ability to adapt to unusual requirements,
• Huge importance in high-tech industry – they serve a role in HDD drives, motor assemblies, medical equipment, and technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in compact constructions

Disadvantages of neodymium magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Limited ability of making nuts in the magnet and complex forms - preferred is casing - magnetic holder.
• Potential hazard related to microscopic parts of magnets pose a threat, if swallowed, which becomes key in the context of child safety. Furthermore, tiny parts of these devices are able to be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what contributes to it?

Information about lifting capacity was defined for optimal configuration, taking into account:

• with the use of a sheet made of special test steel, ensuring maximum field concentration
• with a thickness minimum 10 mm
• with an ground touching surface
• under conditions of no distance (metal-to-metal)
• for force acting at a right angle (in the magnet axis)
• at room temperature

Key elements affecting lifting force

In practice, the real power depends on many variables, ranked from the most important:

• Clearance – the presence of foreign body (rust, tape, gap) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface is typically many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Plate material – low-carbon steel gives the best results. Alloy admixtures reduce magnetic properties and holding force.
• Surface finish – full contact is possible only on polished steel. Any scratches and bumps create air cushions, reducing force.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. When it is hot 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 optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.