MP 30x6x10 / N38 - ring magnet

Strengths as well as weaknesses of NdFeB magnets.

Apart from their consistent holding force, neodymium magnets have these key benefits:

• They do not lose power, even after nearly ten years – the reduction in lifting capacity is only ~1% (according to tests),
• Magnets perfectly protect themselves against demagnetization caused by external fields,
• The use of an shiny layer of noble metals (nickel, gold, silver) causes the element to look better,
• They show high magnetic induction at the operating surface, which improves attraction properties,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, enabling operation at temperatures reaching 230°C and above...
• Thanks to the possibility of flexible forming and customization to specialized needs, neodymium magnets can be modeled in a variety of geometric configurations, which makes them more universal,
• Universal use in advanced technology sectors – they serve a role in HDD drives, electromotive mechanisms, advanced medical instruments, and technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which enables their usage in small systems

What to avoid - cons of neodymium magnets: application proposals

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• NdFeB magnets demagnetize 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Due to limitations in realizing threads and complex forms in magnets, we recommend using cover - magnetic mechanism.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which becomes key in the context of child health protection. Furthermore, small components of these devices are able to complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets is economically unviable,

Maximum lifting capacity of the magnet – what it depends on?

The load parameter shown represents the limit force, measured under ideal test conditions, namely:

• with the application of a yoke made of special test steel, ensuring maximum field concentration
• possessing a massiveness of min. 10 mm to avoid saturation
• characterized by smoothness
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction vertical to the plane
• at standard ambient temperature

Determinants of practical lifting force of a magnet

It is worth knowing that the working load will differ depending on the following factors, in order of importance:

• Space between magnet and steel – every millimeter of distance (caused e.g. by varnish or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Load vector – maximum parameter is obtained only during perpendicular pulling. The force required to slide of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin sheet does not close the flux, causing part of the flux to be lost into the air.
• Material type – ideal substrate is high-permeability steel. Hardened steels may attract less.
• Surface structure – the more even the plate, the larger the contact zone and stronger the hold. Unevenness creates an air distance.
• Thermal factor – hot environment weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.