SMZR 32x125 / N52 - magnetic separator with handle

Strengths as well as weaknesses of NdFeB magnets.

Besides their tremendous strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even during nearly 10 years – the drop in lifting capacity is only ~1% (theoretically),
• They are resistant to demagnetization induced by presence of other magnetic fields,
• A magnet with a smooth gold surface has an effective appearance,
• The surface of neodymium magnets generates a unique magnetic field – this is one of their assets,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of custom modeling as well as modifying to precise conditions,
• Fundamental importance in modern industrial fields – they are utilized in data components, electric drive systems, medical equipment, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which enables their usage in small systems

Cons of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a steel housing, which not only secures them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Due to limitations in producing nuts and complicated forms in magnets, we propose using cover - magnetic mechanism.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the context of child health protection. It is also worth noting that small elements of these products are able to be problematic in diagnostics medical in case of swallowing.
• With mass production the cost of neodymium magnets can be a barrier,

Magnetic strength at its maximum – what affects it?

Magnet power is the result of a measurement for optimal configuration, assuming:

• on a base made of structural steel, effectively closing the magnetic flux
• whose thickness equals approx. 10 mm
• with an polished touching surface
• with zero gap (without paint)
• under axial force vector (90-degree angle)
• at room temperature

Key elements affecting lifting force

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

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – remember that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Material composition – different alloys reacts the same. Alloy additives weaken the interaction with the magnet.
• Surface structure – the smoother and more polished the surface, the larger the contact zone and stronger the hold. Unevenness acts like micro-gaps.
• Thermal factor – high temperature weakens pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate reduces the holding force.