AM ucho [M8] - magnetic accessories

Strengths as well as weaknesses of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• Neodymium magnets remain highly resistant to magnetic field loss caused by external magnetic fields,
• By using a lustrous coating of gold, the element presents an modern look,
• Magnets have excellent magnetic induction on the outer side,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in shaping and the capacity to adapt to specific needs,
• Versatile presence in electronics industry – they are commonly used in computer drives, electric motors, advanced medical instruments, also industrial machines.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets: weaknesses and usage proposals

• To avoid cracks under impact, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• NdFeB magnets lose force 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 very resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of producing nuts in the magnet and complicated forms - preferred is a housing - mounting mechanism.
• Health risk resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small elements of these magnets can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Maximum lifting force for a neodymium magnet – what affects it?

The declared magnet strength refers to the maximum value, obtained under optimal environment, specifically:

• using a sheet made of low-carbon steel, functioning as a magnetic yoke
• possessing a thickness of minimum 10 mm to ensure full flux closure
• characterized by even structure
• under conditions of ideal adhesion (metal-to-metal)
• during pulling in a direction vertical to the plane
• at temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

Holding efficiency is influenced by working environment parameters, such as (from priority):

• Clearance – the presence of any layer (rust, tape, air) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds much less (often approx. 20-30% of maximum force).
• Steel thickness – too thin sheet causes magnetic saturation, causing part of the power to be escaped into the air.
• Plate material – mild steel attracts best. Alloy admixtures lower magnetic properties and lifting capacity.
• Surface finish – ideal contact is obtained only on polished steel. Rough texture create air cushions, weakening the magnet.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.