NCM 10x13.5x5 / N38 - channel magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their strength is durable, and after approximately 10 years, it drops only by ~1% (theoretically),
• They remain magnetized despite exposure to strong external fields,
• Because of the reflective layer of nickel, the component looks high-end,
• Magnetic induction on the surface of these magnets is impressively powerful,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their usage potential,
• Key role in new technology industries – they find application in data storage devices, electric motors, clinical machines or even other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a strong impact. If the magnets are exposed to external force, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks and additionally enhances its overall robustness,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can corrode. Therefore, for outdoor applications, we advise waterproof types made of non-metallic composites,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing fine shapes directly in the magnet,
• Health risk from tiny pieces may arise, especially if swallowed, which is significant in the family environments. Additionally, small elements from these devices may complicate medical imaging after being swallowed,
• In cases of large-volume purchasing, neodymium magnet cost may be a barrier,

Maximum holding power of the magnet – what contributes to it?

The given pulling force of the magnet corresponds to the maximum force, assessed under optimal conditions, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• with zero air gap
• with vertical force applied
• in normal thermal conditions

Practical lifting capacity: influencing factors

The lifting capacity of a magnet is influenced by in practice key elements, according to their importance:

• 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.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.