UMH 20x7x35 [M4] / N38 - magnetic holder with hook

Pros and cons of neodymium magnets.

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

• Their magnetic field remains stable, and after approximately ten years it drops only by ~1% (according to research),
• They feature excellent resistance to magnetic field loss when exposed to opposing magnetic fields,
• Thanks to the shiny finish, the layer of nickel, gold-plated, or silver gives an clean appearance,
• They show high magnetic induction at the operating surface, which affects their effectiveness,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Considering the potential of precise molding and customization to individualized needs, NdFeB magnets can be created in a broad palette of forms and dimensions, which amplifies use scope,
• Universal use in innovative solutions – they are used in computer drives, drive modules, diagnostic systems, and modern systems.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a strong case, which not only secures them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of creating nuts in the magnet and complicated forms - preferred is cover - magnetic holder.
• Potential hazard to health – tiny shards of magnets pose a threat, if swallowed, which gains importance in the context of child safety. It is also worth noting that tiny parts 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

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

Holding force of 14.5 kg is a result of laboratory testing performed under specific, ideal conditions:

• with the use of a sheet made of special test steel, ensuring maximum field concentration
• whose thickness reaches at least 10 mm
• with an polished touching surface
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction perpendicular to the mounting surface
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

In real-world applications, the actual lifting capacity results from a number of factors, ranked from the most important:

• Air gap (betwixt the magnet and the plate), as even a microscopic distance (e.g. 0.5 mm) leads to a decrease in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
• Angle of force application – highest force is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material composition – not every steel reacts the same. Alloy additives worsen the attraction effect.
• Smoothness – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, however under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.