MW 20x5 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose power, even over nearly ten years – the reduction in lifting capacity is only ~1% (according to tests),
• They retain their magnetic properties even under close interference source,
• By covering with a decorative layer of silver, the element acquires an modern look,
• Neodymium magnets deliver maximum magnetic induction on a small surface, which increases force concentration,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of detailed modeling as well as optimizing to specific needs,
• Significant place in modern industrial fields – they are utilized in magnetic memories, brushless drives, precision medical tools, as well as other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which makes them useful in compact constructions

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power 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
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which prevent oxidation and corrosion.
• Limited ability of creating nuts in the magnet and complicated forms - preferred is cover - mounting mechanism.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. It is also worth noting that small components of these devices can disrupt the diagnostic process medical in case of swallowing.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Magnetic strength at its maximum – what it depends on?

The declared magnet strength represents the maximum value, recorded under laboratory conditions, specifically:

• on a base made of mild steel, perfectly concentrating the magnetic field
• possessing a thickness of min. 10 mm to avoid saturation
• with a surface perfectly flat
• with direct contact (without coatings)
• for force acting at a right angle (pull-off, not shear)
• at standard ambient temperature

Determinants of practical lifting force of a magnet

Please note that the working load will differ depending on elements below, in order of importance:

• Space between surfaces – every millimeter of separation (caused e.g. by veneer or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to detachment vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Base massiveness – insufficiently thick plate does not close the flux, causing part of the power to be wasted into the air.
• Chemical composition of the base – mild steel attracts best. Higher carbon content lower magnetic properties and lifting capacity.
• Smoothness – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, reducing force.
• Temperature influence – hot environment reduces magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.