NCM 20x13.5x5 / N38 - channel magnetic holder

Pros and cons of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• Neodymium magnets prove to be extremely resistant to magnetic field loss caused by external magnetic fields,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets are characterized by extremely high magnetic induction on the outer side,
• Thanks to resistance to high temperature, they are able to function (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to modularity in constructing and the capacity to customize to individual projects,
• Significant place in future technologies – they are utilized in data components, electric drive systems, medical devices, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in miniature devices

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only protects them against impacts but also increases their durability
• NdFeB magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (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 extremely resistant to heat
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• Due to limitations in realizing nuts and complicated shapes in magnets, we recommend using cover - magnetic mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small components of these products can complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Highest magnetic holding force – what it depends on?

The force parameter is a theoretical maximum value conducted under the following configuration:

• on a plate made of mild steel, perfectly concentrating the magnetic field
• with a cross-section of at least 10 mm
• with a surface cleaned and smooth
• with direct contact (without paint)
• during pulling in a direction perpendicular to the mounting surface
• at ambient temperature room level

What influences lifting capacity in practice

In practice, the actual holding force depends on a number of factors, presented from crucial:

• Air gap (between the magnet and the plate), since even a microscopic clearance (e.g. 0.5 mm) leads to a drastic drop in force by up to 50% (this also applies to varnish, corrosion or dirt).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the interaction with the magnet.
• Base smoothness – the more even the surface, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal environment – heating the magnet causes a temporary drop of force. Check the thermal limit for a given model.

* Lifting capacity was measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under attempts to slide the magnet the load capacity is reduced by as much as fivefold. In addition, even a minimal clearance {between} the magnet and the plate decreases the load capacity.