SM 25x400 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of NdFeB magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• Their magnetic field is durable, and after around ten years it drops only by ~1% (theoretically),
• They feature excellent resistance to weakening of magnetic properties as a result of external magnetic sources,
• In other words, due to the shiny surface of silver, the element becomes visually attractive,
• Neodymium magnets create maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Thanks to resistance to high temperature, they are able to function (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to modularity in designing and the capacity to adapt to complex applications,
• Universal use in advanced technology sectors – they are used in mass storage devices, brushless drives, medical devices, also other advanced devices.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of creating threads in the magnet and complicated forms - preferred is cover - magnet mounting.
• Possible danger to health – tiny shards of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. Furthermore, small components of these devices are able to disrupt the diagnostic process medical in case of swallowing.
• Due to complex production process, their price is relatively high,

Detachment force of the magnet in optimal conditions – what it depends on?

Magnet power is the result of a measurement for the most favorable conditions, including:

• with the contact of a yoke made of special test steel, ensuring full magnetic saturation
• whose transverse dimension is min. 10 mm
• with an polished touching surface
• with direct contact (no paint)
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature room level

Lifting capacity in real conditions – factors

In real-world applications, the actual holding force is determined by a number of factors, presented from most significant:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) drastically reduces the pulling force, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to pulling vertically. When applying parallel force, the magnet exhibits much less (typically approx. 20-30% of maximum force).
• Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the power to be escaped into the air.
• Metal type – not every steel reacts the same. Alloy additives weaken the interaction with the magnet.
• Smoothness – full contact is obtained only on polished steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was determined using a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, whereas under parallel forces the holding force is lower. Moreover, even a small distance {between} the magnet and the plate reduces the load capacity.