SMZR 25x225 / N52 - magnetic separator with handle

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They do not lose their even during approximately 10 years – the reduction of power is only ~1% (theoretically),
• They are extremely resistant to demagnetization caused by external magnetic sources,
• In other words, due to the metallic gold coating, the magnet obtains an professional appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• With the option for tailored forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Wide application in modern technologies – they are utilized in data storage devices, electromechanical systems, medical equipment along with other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and reinforces its overall durability,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent decline in performance (depending on height). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• They rust in a damp environment. For outdoor use, we recommend using moisture-resistant magnets, such as those made of non-metallic materials,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Possible threat from tiny pieces may arise, especially if swallowed, which is significant in the context of child safety. Furthermore, tiny components from these assemblies can hinder health screening once in the system,
• Due to a complex production process, their cost is considerably higher,

Breakaway strength of the magnet in ideal conditions – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, determined in ideal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• at room temperature

Practical lifting capacity: influencing factors

Practical lifting force is determined by elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, since 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 a smooth plate of optimal thickness, under perpendicular forces, in contrast under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.