SM 32x300 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of rare earth magnets.

Apart from their superior holding force, neodymium magnets have these key benefits:

• They retain attractive force for around 10 years – the loss is just ~1% (in theory),
• Magnets perfectly defend themselves against loss of magnetization caused by ambient magnetic noise,
• By covering with a smooth layer of nickel, the element gains an elegant look,
• They are known for high magnetic induction at the operating surface, which improves attraction properties,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to modularity in forming and the capacity to customize to specific needs,
• Versatile presence in modern technologies – they are commonly used in computer drives, drive modules, advanced medical instruments, and complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which allows their use in small systems

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets in a protective case. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets lose their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture, in case of application outdoors
• Due to limitations in producing threads and complicated forms in magnets, we recommend using casing - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, in case of ingestion, which gains importance in the context of child safety. Additionally, small elements of these magnets are able to complicate diagnosis medical when they are in the body.
• With large orders the cost of neodymium magnets is a challenge,

Best holding force of the magnet in ideal parameters – what affects it?

The specified lifting capacity concerns the maximum value, obtained under ideal test conditions, meaning:

• on a plate made of mild steel, effectively closing the magnetic field
• whose thickness reaches at least 10 mm
• with an ground touching surface
• without the slightest insulating layer between the magnet and steel
• during pulling in a direction perpendicular to the plane
• at temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

It is worth knowing that the application force will differ subject to elements below, starting with the most relevant:

• Air gap (between the magnet and the metal), as even a very small clearance (e.g. 0.5 mm) results in a decrease in lifting capacity by up to 50% (this also applies to paint, corrosion or debris).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Plate thickness – too thin plate does not close the flux, causing part of the power to be escaped into the air.
• Material type – ideal substrate is high-permeability steel. Cast iron may have worse magnetic properties.
• Surface finish – ideal contact is possible only on polished steel. Rough texture reduce the real contact area, reducing force.
• Thermal factor – hot environment weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.