MW 14x3 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• Their power is maintained, and after approximately 10 years, it drops only by ~1% (theoretically),
• They show strong resistance to demagnetization from outside magnetic sources,
• Because of the reflective layer of silver, the component looks high-end,
• They possess significant magnetic force measurable at the magnet’s surface,
• Thanks to their exceptional 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 personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Key role in new technology industries – they are utilized in HDDs, electric drives, healthcare devices and technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from damage and increases its overall durability,
• They lose magnetic force at extreme temperatures. Most neodymium magnets experience permanent loss 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of plastic for outdoor use,
• Limited ability to create complex details in the magnet – the use of a housing is recommended,
• Possible threat from tiny pieces may arise, especially if swallowed, which is significant in the health of young users. Furthermore, tiny components from these devices have the potential to disrupt scanning after being swallowed,
• Due to the price of neodymium, their cost is relatively high,

Magnetic strength at its maximum – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, calculated in the best circumstances, 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 zero air gap
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key 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, as 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 was assessed with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.