SM 25x225 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their attractive force for almost 10 years – the loss is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the reflective layer of gold, the component looks visually appealing,
• Magnetic induction on the surface of these magnets is notably high,
• Thanks to their high temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• With the option for fine forming and targeted design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Wide application in new technology industries – they are used in computer drives, rotating machines, diagnostic apparatus or even other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of rare earth magnets:

• They are fragile when subjected to a strong impact. If the magnets are exposed to external force, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time strengthens its overall resistance,
• They lose power at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to humidity can degrade. Therefore, for outdoor applications, it's best to use waterproof types made of coated materials,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing complex structures directly in the magnet,
• Health risk from tiny pieces may arise, when consumed by mistake, which is crucial in the protection of children. Furthermore, small elements from these magnets have the potential to complicate medical imaging when ingested,
• In cases of tight budgets, neodymium magnet cost is a challenge,

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

The given pulling force of the magnet represents the maximum force, calculated 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 refined outer layer
• with no separation
• with vertical force applied
• at room temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet is determined by in practice key elements, ordered from most important to least significant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause 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 performed on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.