MPL 20x10x5 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• Their magnetic field is maintained, and after around 10 years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by ambient electromagnetic environments effectively,
• Thanks to the glossy finish and nickel coating, they have an elegant appearance,
• They possess intense magnetic force measurable at the magnet’s surface,
• Thanks to their enhanced temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• With the option for tailored forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Significant impact in cutting-edge sectors – they serve a purpose in HDDs, rotating machines, clinical machines as well as high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time enhances its overall strength,
• They lose field intensity at extreme temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a damp environment – during outdoor use, we recommend using waterproof magnets, such as those made of polymer,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing fine shapes directly in the magnet,
• Safety concern due to small fragments may arise, especially if swallowed, which is significant in the health of young users. It should also be noted that small elements from these assemblies have the potential to disrupt scanning if inside the body,
• In cases of mass production, neodymium magnet cost may be a barrier,

Maximum magnetic pulling force – what contributes to it?

The given pulling force of the magnet represents the maximum force, measured in ideal conditions, specifically:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Key elements affecting lifting force

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

• 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.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate lowers the load capacity.