AM ucho [M8] - magnetic accessories

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 during approximately ten years – the decrease in lifting capacity is only ~1% (theoretically),
• They are extremely resistant to demagnetization induced by presence of other magnetic fields,
• A magnet with a metallic gold surface has an effective appearance,
• They are known for high magnetic induction at the operating surface, which increases their power,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to modularity in shaping and the ability to adapt to unusual requirements,
• Versatile presence in electronics industry – they serve a role in computer drives, electromotive mechanisms, medical equipment, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in small systems

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• To avoid cracks under impact, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• Limited possibility of making nuts in the magnet and complicated forms - recommended is casing - mounting mechanism.
• Possible danger resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small elements of these devices can be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Breakaway strength of the magnet in ideal conditions – what it depends on?

The declared magnet strength concerns the limit force, measured under laboratory conditions, namely:

• on a plate made of mild steel, optimally conducting the magnetic field
• with a thickness minimum 10 mm
• characterized by even structure
• without the slightest air gap between the magnet and steel
• during detachment in a direction vertical to the plane
• at standard ambient temperature

Lifting capacity in real conditions – factors

Effective lifting capacity impacted by working environment parameters, including (from priority):

• Gap between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of generating force.
• Metal type – different alloys reacts the same. Alloy additives weaken the attraction effect.
• Surface finish – full contact is obtained only on smooth steel. Rough texture create air cushions, reducing force.
• Thermal factor – high temperature reduces magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.