MP 5x2.7/1.2x5 C / N38 - ring magnet

Advantages as well as disadvantages of neodymium magnets.

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

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• They possess excellent resistance to magnetism drop as a result of external magnetic sources,
• The use of an refined finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets are distinguished by extremely high magnetic induction on the surface,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to the ability of flexible forming and customization to custom requirements, neodymium magnets can be produced in a variety of shapes and sizes, which amplifies use scope,
• Key role in electronics industry – they serve a role in computer drives, electric motors, medical equipment, and other advanced devices.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

What to avoid - cons of neodymium magnets and proposals for their use:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (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 very 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 stable to moisture, when using outdoors
• We recommend casing - magnetic holder, due to difficulties in realizing threads inside the magnet and complicated shapes.
• Health risk related to microscopic parts of magnets can be dangerous, if swallowed, which gains importance in the context of child safety. Additionally, small elements of these products are able to complicate diagnosis medical after entering the body.
• With budget limitations the cost of neodymium magnets is economically unviable,

Maximum lifting capacity of the magnet – what affects it?

The declared magnet strength refers to the maximum value, recorded under optimal environment, namely:

• with the use of a yoke made of special test steel, ensuring maximum field concentration
• possessing a thickness of minimum 10 mm to ensure full flux closure
• with an polished contact surface
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• at conditions approx. 20°C

Key elements affecting lifting force

Please note that the application force will differ depending on the following factors, in order of importance:

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet holds much less (often approx. 20-30% of maximum force).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of generating force.
• Metal type – different alloys reacts the same. High carbon content worsen the interaction with the magnet.
• Surface structure – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Unevenness creates an air distance.
• Temperature – heating the magnet causes a temporary drop of force. It is worth remembering the thermal limit for a given model.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.