MW 6x3 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (in laboratory conditions),
• They are extremely resistant to demagnetization caused by external magnetic fields,
• Because of the lustrous layer of gold, the component looks visually appealing,
• They have very high magnetic induction on the surface of the magnet,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• The ability for precise shaping or adjustment to individual needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which extends the scope of their use cases,
• Important function in new technology industries – they are utilized in HDDs, rotating machines, clinical machines as well as other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are fragile when subjected to a sudden 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 additionally reinforces its overall strength,
• They lose strength at elevated temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a moist environment, especially when used outside, we recommend using sealed magnets, such as those made of polymer,
• Limited ability to create threads in the magnet – the use of a mechanical support is recommended,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is notable in the context of child safety. Furthermore, small elements from these products might hinder health screening once in the system,
• In cases of large-volume purchasing, neodymium magnet cost is a challenge,

Magnetic strength at its maximum – what contributes to it?

The given lifting capacity of the magnet means the maximum lifting force, determined in a perfect environment, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• in normal thermal conditions

Magnet lifting force in use – key factors

In practice, the holding capacity of a magnet is affected by the following aspects, from crucial to less important:

• 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 performed on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under shearing force the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.