AM ucho [M8] - magnetic accessories

Strengths and weaknesses of NdFeB magnets.

Besides their tremendous field intensity, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (in laboratory conditions),
• Magnets very well protect themselves against loss of magnetization caused by foreign field sources,
• Thanks to the glossy finish, the surface of Ni-Cu-Ni, gold-plated, or silver-plated gives an visually attractive appearance,
• They show high magnetic induction at the operating surface, which improves attraction properties,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Possibility of custom machining as well as adjusting to individual requirements,
• Significant place in modern industrial fields – they are used in magnetic memories, brushless drives, medical devices, as well as industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which allows their use in miniature devices

Disadvantages of NdFeB magnets:

• At very strong impacts they can break, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We suggest cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complicated shapes.
• Potential hazard to health – tiny shards of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small elements of these magnets are able to complicate diagnosis medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The load parameter shown concerns the maximum value, obtained under optimal environment, meaning:

• using a base made of mild steel, serving as a magnetic yoke
• whose transverse dimension equals approx. 10 mm
• with an polished contact surface
• without the slightest clearance between the magnet and steel
• under vertical force vector (90-degree angle)
• in stable room temperature

Impact of factors on magnetic holding capacity in practice

Real force is influenced by specific conditions, such as (from most important):

• Space between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Chemical composition of the base – mild steel gives the best results. Alloy steels reduce magnetic properties and lifting capacity.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and higher the lifting capacity. Roughness creates an air distance.
• Thermal environment – temperature increase results in weakening of force. Check the thermal limit for a given model.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.