UMS 16x6.5x3.5x5 / N38 - conical magnetic holder

Strengths and weaknesses of NdFeB magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They retain full power for around 10 years – the drop is just ~1% (based on simulations),
• Magnets perfectly defend themselves against loss of magnetization caused by ambient magnetic noise,
• In other words, due to the aesthetic layer of silver, the element becomes visually attractive,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of exact forming and adjusting to specific applications,
• Wide application in high-tech industry – they are used in mass storage devices, electromotive mechanisms, diagnostic systems, as well as other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Problematic aspects of neodymium magnets and proposals for their use:

• To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• Neodymium magnets decrease their power 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
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We suggest casing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complicated shapes.
• Possible danger to health – tiny shards of magnets can be dangerous, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, small elements of these products can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum magnetic pulling force – what affects it?

The load parameter shown represents the peak performance, recorded under ideal test conditions, namely:

• on a plate made of structural steel, perfectly concentrating the magnetic field
• with a cross-section minimum 10 mm
• with a plane perfectly flat
• with zero gap (no impurities)
• for force acting at a right angle (pull-off, not shear)
• at standard ambient temperature

Lifting capacity in practice – influencing factors

In practice, the actual holding force is determined by several key aspects, listed from crucial:

• Gap (between the magnet and the plate), since even a tiny distance (e.g. 0.5 mm) leads to a decrease in force by up to 50% (this also applies to paint, rust or dirt).
• Load vector – highest force is reached only during pulling at a 90° angle. The shear force of the magnet along the surface is standardly several times lower (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin sheet causes magnetic saturation, causing part of the power to be wasted into the air.
• Material composition – different alloys reacts the same. High carbon content weaken the interaction with the magnet.
• Base smoothness – the more even the surface, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under perpendicular forces, in contrast under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a slight gap {between} the magnet and the plate reduces the lifting capacity.