SM 32x225 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after ten years, the performance loss is only ~1% (in laboratory conditions),
• Their ability to resist magnetic interference from external fields is notable,
• In other words, due to the glossy nickel coating, the magnet obtains an aesthetic appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• The ability for accurate shaping and customization to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Important function in advanced technical fields – they are utilized in hard drives, electric motors, medical equipment along with technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to physical collisions, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture while also enhances its overall strength,
• They lose field intensity at increased temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can corrode. Therefore, for outdoor applications, we recommend waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Safety concern due to small fragments may arise, if ingested accidentally, which is crucial in the health of young users. Furthermore, minuscule fragments from these magnets have the potential to disrupt scanning once in the system,
• Due to expensive raw materials, their cost is above average,

Highest magnetic holding force – what affects it?

The given holding capacity of the magnet means the highest holding force, determined under optimal conditions, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• with zero air gap
• with vertical force applied
• under standard ambient temperature

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is conditioned by these factors, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, however under parallel forces the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate lowers the lifting capacity.