SM 25x350 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain magnetic properties for almost 10 years – the loss is just ~1% (in theory),
• They possess excellent resistance to magnetic field loss due to external magnetic sources,
• In other words, due to the reflective surface of silver, the element is aesthetically pleasing,
• They are known for high magnetic induction at the operating surface, which affects their effectiveness,
• 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...
• Thanks to versatility in forming and the ability to customize to individual projects,
• Universal use in innovative solutions – they are commonly used in mass storage devices, drive modules, medical devices, also modern systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which allows their use in miniature devices

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously increases its 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
• 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 a housing - magnetic mechanism, due to difficulties in realizing nuts inside the magnet and complicated shapes.
• Health risk to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which is particularly important in the context of child health protection. Furthermore, tiny parts of these magnets can disrupt the diagnostic process medical after entering the body.
• Due to neodymium price, their price is relatively high,

Optimal lifting capacity of a neodymium magnet – what it depends on?

The specified lifting capacity refers to the peak performance, obtained under ideal test conditions, meaning:

• on a base made of structural steel, effectively closing the magnetic field
• whose thickness is min. 10 mm
• characterized by even structure
• without the slightest clearance between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• at room temperature

Key elements affecting lifting force

In practice, the actual lifting capacity depends on several key aspects, presented from the most important:

• Gap between surfaces – every millimeter of separation (caused e.g. by veneer or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Direction of force – highest force is available only during perpendicular pulling. The shear force of the magnet along the plate is typically several times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of converting into lifting capacity.
• Metal type – different alloys reacts the same. Alloy additives worsen the interaction with the magnet.
• Surface quality – the smoother and more polished the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal environment – heating the magnet results in weakening of force. Check the thermal limit for a given model.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate reduces the load capacity.