MP 5x2.7/1.2x5 C / N38 - ring magnet

Advantages and disadvantages of rare earth magnets.

Apart from their consistent power, neodymium magnets have these key benefits:

• They have stable power, and over more than ten years their attraction force decreases symbolically – ~1% (according to theory),
• Magnets very well resist against loss of magnetization caused by external fields,
• In other words, due to the reflective surface of silver, the element is aesthetically pleasing,
• Neodymium magnets deliver maximum magnetic induction on a small surface, which allows for strong attraction,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, allowing for action at temperatures approaching 230°C and above...
• In view of the ability of accurate shaping and adaptation to specialized requirements, neodymium magnets can be produced in a broad palette of geometric configurations, which amplifies use scope,
• Universal use in advanced technology sectors – they are utilized in HDD drives, brushless drives, medical devices, also other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also improves its resistance to damage
• Neodymium magnets decrease their power 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 durability even at temperatures up to 230°C
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We recommend casing - magnetic holder, due to difficulties in realizing nuts inside the magnet and complex shapes.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small components of these magnets can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The specified lifting capacity represents the limit force, measured under optimal environment, namely:

• using a plate made of mild steel, acting as a magnetic yoke
• with a cross-section of at least 10 mm
• characterized by lack of roughness
• with zero gap (no paint)
• during detachment in a direction vertical to the mounting surface
• at conditions approx. 20°C

Key elements affecting lifting force

In practice, the real power depends on a number of factors, presented from crucial:

• Clearance – the presence of any layer (paint, tape, gap) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is available only during perpendicular pulling. The shear force of the magnet along the plate is usually many times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Steel grade – the best choice is pure iron steel. Hardened steels may generate lower lifting capacity.
• Smoothness – ideal contact is possible only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Temperature influence – hot environment reduces magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a small distance {between} the magnet and the plate decreases the lifting capacity.