UMP 97x40 [M8+M10] GW F300 Lina / N38 - search holder

Advantages and disadvantages of NdFeB magnets.

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

• They retain attractive force for nearly 10 years – the loss is just ~1% (according to analyses),
• Magnets very well resist against loss of magnetization caused by ambient magnetic noise,
• By covering with a decorative layer of nickel, the element gains an nice look,
• The surface of neodymium magnets generates a unique magnetic field – this is a key feature,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to form),
• Possibility of detailed machining as well as adapting to specific needs,
• Significant place in high-tech industry – they are used in HDD drives, electric motors, medical equipment, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in small systems

Disadvantages of neodymium magnets:

• To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we recommend 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 - mounting mechanism.
• Health risk to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child safety. Furthermore, small elements of these devices can complicate diagnosis medical when they are in the body.
• Due to expensive raw materials, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The declared magnet strength refers to the maximum value, measured under ideal test conditions, meaning:

• using a sheet made of low-carbon steel, serving as a circuit closing element
• whose thickness is min. 10 mm
• characterized by even structure
• with direct contact (without impurities)
• for force acting at a right angle (in the magnet axis)
• at ambient temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

In practice, the real power depends on many variables, ranked from crucial:

• Distance – the presence of foreign body (rust, tape, air) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Loading method – catalog parameter refers to detachment vertically. When attempting to slide, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Steel thickness – insufficiently thick sheet does not close the flux, causing part of the power to be lost to the other side.
• Material composition – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Surface finish – ideal contact is obtained only on polished steel. Rough texture create air cushions, reducing force.
• Heat – neodymium magnets have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the lifting capacity is smaller. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.