UMH 60x15x69 [M8] / N38 - magnetic holder with hook

Strengths as well as weaknesses of neodymium magnets.

Besides their stability, neodymium magnets are valued for these benefits:

• They retain full power for almost ten years – the loss is just ~1% (in theory),
• They have excellent resistance to magnetic field loss as a result of opposing magnetic fields,
• In other words, due to the reflective layer of silver, the element looks attractive,
• Magnets have extremely high magnetic induction on the outer side,
• Thanks to resistance to high temperature, they can operate (depending on the form) even at temperatures up to 230°C and higher...
• Possibility of custom shaping and modifying to precise applications,
• Key role in future technologies – they are utilized in hard drives, electric motors, medical devices, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which makes them useful in small systems

Problematic aspects of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a strong case, which not only secures them against impacts but also increases their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of creating nuts in the magnet and complicated forms - preferred is a housing - mounting mechanism.
• Potential hazard resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. Additionally, small elements of these magnets can complicate diagnosis medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting force for a neodymium magnet – what it depends on?

Breakaway force was defined for ideal contact conditions, taking into account:

• on a block made of structural steel, effectively closing the magnetic field
• whose transverse dimension reaches at least 10 mm
• with an ground contact surface
• with zero gap (no impurities)
• for force applied at a right angle (pull-off, not shear)
• at room temperature

Practical aspects of lifting capacity – factors

Effective lifting capacity impacted by working environment parameters, such as (from most important):

• Space between surfaces – every millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Plate material – mild steel attracts best. Higher carbon content reduce magnetic permeability and lifting capacity.
• Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, reducing force.
• Thermal environment – heating the magnet results in weakening of induction. Check the thermal limit for a given model.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the lifting capacity.