MP 12x8/4x3 / N38 - ring magnet

Pros and cons of NdFeB magnets.

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

• Their power remains stable, and after around 10 years it drops only by ~1% (theoretically),
• Magnets very well defend themselves against demagnetization caused by foreign field sources,
• The use of an shiny layer of noble metals (nickel, gold, silver) causes the element to look better,
• Magnets are distinguished by excellent magnetic induction on the active area,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in constructing and the ability to customize to individual projects,
• Huge importance in innovative solutions – they find application in magnetic memories, brushless drives, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in small systems

Disadvantages of neodymium magnets:

• At strong impacts they can break, therefore we advise placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• We suggest cover - magnetic mount, due to difficulties in producing threads inside the magnet and complicated forms.
• Possible danger to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small components of these magnets can complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Magnetic strength at its maximum – what affects it?

Magnet power was defined for optimal configuration, assuming:

• with the contact of a yoke made of special test steel, ensuring full magnetic saturation
• possessing a thickness of at least 10 mm to avoid saturation
• characterized by lack of roughness
• without any insulating layer between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at temperature room level

Practical aspects of lifting capacity – factors

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

• Distance – existence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The shear force of the magnet along the plate is typically several times lower (approx. 1/5 of the lifting capacity).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Material type – the best choice is high-permeability steel. Stainless steels may attract less.
• Surface finish – ideal contact is obtained only on smooth steel. Rough texture create air cushions, reducing force.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was determined using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. In addition, even a minimal clearance {between} the magnet and the plate reduces the load capacity.