MP 12x8/4x3 / N38 - ring magnet

Strengths and weaknesses of NdFeB magnets.

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

• Their strength remains stable, and after around ten years it decreases only by ~1% (theoretically),
• They are extremely resistant to demagnetization induced by external disturbances,
• By applying a decorative coating of gold, the element gains an proper look,
• The surface of neodymium magnets generates a strong magnetic field – this is a distinguishing feature,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• In view of the potential of flexible molding and adaptation to specialized solutions, neodymium magnets can be manufactured in a variety of shapes and sizes, which makes them more universal,
• Key role in future technologies – they are commonly used in mass storage devices, brushless drives, medical devices, as well as modern systems.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only protects the magnet but also increases its resistance to damage
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• They rust in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited ability of producing nuts in the magnet and complicated shapes - preferred is cover - mounting mechanism.
• Potential hazard related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small components of these devices can complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

Detachment force of the magnet in optimal conditions – what contributes to it?

The declared magnet strength represents the peak performance, recorded under ideal test conditions, namely:

• with the application of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• with an ground contact surface
• under conditions of gap-free contact (surface-to-surface)
• for force applied at a right angle (pull-off, not shear)
• in stable room temperature

Determinants of practical lifting force of a magnet

In real-world applications, the actual lifting capacity results from many variables, ranked from most significant:

• Clearance – existence of any layer (rust, dirt, air) interrupts the magnetic circuit, which lowers capacity steeply (even by 50% at 0.5 mm).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Chemical composition of the base – low-carbon steel attracts best. Alloy steels decrease magnetic permeability and lifting capacity.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Heat – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity was measured using a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, however under shearing force the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate reduces the lifting capacity.