MP 12x8/4x3 / N38 - ring magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They do not lose their strength around 10 years – the reduction of strength is only ~1% (according to tests),
• They are very resistant to demagnetization caused by external magnetic sources,
• Thanks to the shiny finish and gold coating, they have an visually attractive appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the magnetic form),
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Significant impact in modern technologies – they are utilized in data storage devices, rotating machines, clinical machines along with other advanced devices,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to external force, it is suggested to place them in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time increases its overall resistance,
• They lose strength at extreme 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,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Potential hazard due to small fragments may arise, when consumed by mistake, which is important in the protection of children. Additionally, small elements from these assemblies can disrupt scanning after being swallowed,
• In cases of mass production, neodymium magnet cost may be a barrier,

Best holding force of the magnet in ideal parameters – what it depends on?

The given holding capacity of the magnet corresponds to the highest holding force, calculated under optimal conditions, namely:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• under standard ambient temperature

Lifting capacity in real conditions – factors

The lifting capacity of a magnet depends on in practice key elements, ordered from most important to least 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 performed on a smooth plate of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the holding force.