UMH 75x18x68 [M8] / N38 - magnetic holder with hook

Pros as well as cons of rare earth magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• Neodymium magnets are distinguished by highly resistant to loss of magnetic properties caused by magnetic disturbances,
• The use of an shiny layer of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• 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...
• Thanks to the option of accurate molding and customization to unique requirements, neodymium magnets can be produced in a wide range of geometric configurations, which increases their versatility,
• Wide application in high-tech industry – they are utilized in HDD drives, drive modules, medical devices, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which allows their use in small systems

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• At very strong impacts they can crack, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material stable to moisture, in case of application outdoors
• Due to limitations in creating threads and complicated forms in magnets, we propose using casing - magnetic holder.
• Possible danger related to microscopic parts of magnets can be dangerous, in case of ingestion, which becomes key in the context of child safety. It is also worth noting that small elements of these magnets can complicate diagnosis medical after entering the body.
• Due to expensive raw materials, their price is higher than average,

Maximum holding power of the magnet – what contributes to it?

The lifting capacity listed is a theoretical maximum value performed under the following configuration:

• using a sheet made of low-carbon steel, acting as a circuit closing element
• with a cross-section minimum 10 mm
• with an polished contact surface
• without the slightest clearance between the magnet and steel
• under perpendicular force vector (90-degree angle)
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

In practice, the real power is determined by many variables, ranked from most significant:

• Air gap (betwixt the magnet and the metal), as even a tiny distance (e.g. 0.5 mm) results in a reduction in force by up to 50% (this also applies to varnish, rust or dirt).
• Force direction – note that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Base massiveness – too thin sheet does not accept the full field, causing part of the flux to be escaped into the air.
• Material composition – not every steel attracts identically. High carbon content worsen the attraction effect.
• Surface quality – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Temperature influence – hot environment weakens pulling force. Too high temperature can permanently damage the magnet.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a small distance {between} the magnet and the plate lowers the holding force.