MP 20x8/4x5 / N38 - ring magnet

Advantages and disadvantages of rare earth magnets.

Besides their exceptional pulling force, neodymium magnets offer the following advantages:

• They retain full power for almost ten years – the loss is just ~1% (according to analyses),
• They are noted for resistance to demagnetization induced by external disturbances,
• A magnet with a smooth silver surface has better aesthetics,
• Neodymium magnets generate maximum magnetic induction on a contact point, which increases force concentration,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures reaching 230°C and above...
• Thanks to the possibility of accurate shaping and adaptation to custom projects, neodymium magnets can be modeled in a wide range of forms and dimensions, which increases their versatility,
• Fundamental importance in innovative solutions – they are commonly used in hard drives, electromotive mechanisms, advanced medical instruments, and modern systems.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in small systems

Disadvantages of NdFeB magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a strong case, which not only secures them against impacts but also raises their durability
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• We suggest casing - magnetic mount, due to difficulties in realizing nuts inside the magnet and complex forms.
• Health risk related to microscopic parts of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. It is also worth noting that small elements of these magnets are able to complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is economically unviable,

Optimal lifting capacity of a neodymium magnet – what affects it?

The load parameter shown refers to the peak performance, obtained under optimal environment, meaning:

• using a base made of high-permeability steel, acting as a ideal flux conductor
• with a thickness of at least 10 mm
• characterized by lack of roughness
• with total lack of distance (without paint)
• during detachment in a direction perpendicular to the mounting surface
• at conditions approx. 20°C

Determinants of practical lifting force of a magnet

In real-world applications, the actual lifting capacity is determined by a number of factors, presented from the most important:

• Distance – the presence of any layer (paint, dirt, air) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is available only during perpendicular pulling. The resistance to sliding of the magnet along the surface is typically several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Material type – ideal substrate is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Surface condition – smooth surfaces ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Temperature – heating the magnet causes a temporary drop of induction. It is worth remembering the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.