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

Pros and cons of rare earth magnets.

Besides their tremendous field intensity, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• Magnets very well defend themselves against loss of magnetization caused by ambient magnetic noise,
• A magnet with a metallic silver surface is more attractive,
• Magnets have huge magnetic induction on the working surface,
• Thanks to resistance to high temperature, they are capable of working (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in constructing and the capacity to adapt to client solutions,
• Huge importance in future technologies – they are used in computer drives, motor assemblies, diagnostic systems, and industrial machines.
• Compactness – despite small sizes they generate large force, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only shields the magnet but also improves its resistance to damage
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of producing nuts in the magnet and complex forms - preferred is cover - magnetic holder.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. Additionally, small components of these magnets are able to disrupt the diagnostic process medical when they are in the body.
• Due to complex production process, their price exceeds standard values,

Maximum lifting force for a neodymium magnet – what affects it?

Magnet power is the result of a measurement for ideal contact conditions, taking into account:

• on a plate made of mild steel, optimally conducting the magnetic flux
• possessing a thickness of min. 10 mm to avoid saturation
• with an ideally smooth contact surface
• with direct contact (without impurities)
• under axial application of breakaway force (90-degree angle)
• at temperature room level

Determinants of lifting force in real conditions

Please note that the application force will differ depending on the following factors, in order of importance:

• Air gap (between the magnet and the metal), as even a very small distance (e.g. 0.5 mm) leads to a drastic drop in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Steel thickness – insufficiently thick sheet does not accept the full field, causing part of the power to be escaped to the other side.
• Material composition – different alloys reacts the same. Alloy additives worsen the attraction effect.
• Surface condition – ground elements ensure maximum contact, which increases force. Rough surfaces reduce efficiency.
• Operating temperature – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.