AM ucho [M12] - magnetic accessories

Advantages and disadvantages of NdFeB magnets.

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

• They retain attractive force for nearly 10 years – the loss is just ~1% (in theory),
• Neodymium magnets prove to be remarkably resistant to loss of magnetic properties caused by external field sources,
• In other words, due to the reflective surface of silver, the element becomes visually attractive,
• They show high magnetic induction at the operating surface, making them more effective,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures reaching 230°C and above...
• Possibility of custom shaping and adjusting to concrete applications,
• Fundamental importance in modern industrial fields – they serve a role in mass storage devices, electric drive systems, precision medical tools, as well as industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which enables their usage in compact constructions

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a strong case, which not only protects them against impacts but also increases their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complex shapes.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child health protection. It is also worth noting that small elements of these products are able to complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Detachment force of the magnet in optimal conditions – what it depends on?

The force parameter is a measurement result performed under the following configuration:

• on a plate made of structural steel, perfectly concentrating the magnetic field
• possessing a thickness of minimum 10 mm to avoid saturation
• characterized by even structure
• with direct contact (no coatings)
• for force acting at a right angle (in the magnet axis)
• at temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

Real force impacted by working environment parameters, including (from priority):

• Distance – existence of any layer (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Angle of force application – highest force is obtained only during perpendicular pulling. The resistance to sliding of the magnet along the surface is typically several times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Chemical composition of the base – mild steel attracts best. Higher carbon content decrease magnetic permeability and holding force.
• Surface finish – full contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Heat – NdFeB sinters have a negative temperature coefficient. At higher temperatures they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the holding force is lower. In addition, even a slight gap {between} the magnet and the plate reduces the lifting capacity.