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

Strengths as well as weaknesses of NdFeB magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They retain full power for around ten years – the drop is just ~1% (in theory),
• Neodymium magnets are characterized by extremely resistant to demagnetization caused by external magnetic fields,
• In other words, due to the shiny layer of silver, the element is aesthetically pleasing,
• Magnets are distinguished by extremely high magnetic induction on the outer layer,
• 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...
• Considering the potential of precise molding and adaptation to individualized requirements, magnetic components can be manufactured in a variety of shapes and sizes, which makes them more universal,
• Versatile presence in modern industrial fields – they serve a role in data components, electromotive mechanisms, medical equipment, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which enables their usage in miniature devices

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can crack, therefore we advise placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• We recommend a housing - magnetic holder, due to difficulties in producing nuts inside the magnet and complex shapes.
• Possible danger related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small components of these products can disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what it depends on?

Breakaway force was defined for the most favorable conditions, assuming:

• using a sheet made of low-carbon steel, serving as a circuit closing element
• with a cross-section minimum 10 mm
• with a surface perfectly flat
• without the slightest clearance between the magnet and steel
• under vertical force direction (90-degree angle)
• at ambient temperature room level

What influences lifting capacity in practice

In real-world applications, the actual holding force results from a number of factors, ranked from crucial:

• Clearance – the presence of any layer (paint, dirt, air) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Metal type – different alloys attracts identically. High carbon content worsen the attraction effect.
• Surface finish – full contact is possible only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Temperature influence – high temperature reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.