MPL 25x10x5 / 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 durable, and after around 10 years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by external magnetic fields very well,
• By applying a reflective layer of gold, the element gains a sleek look,
• Magnetic induction on the surface of these magnets is impressively powerful,
• With the right combination of magnetic alloys, they reach significant thermal stability, enabling operation at or above 230°C (depending on the structure),
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which broadens their application range,
• Significant impact in new technology industries – they are used in computer drives, electric motors, medical equipment and high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which makes them ideal in small systems

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a powerful impact. If the magnets are exposed to shocks, 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 enhances its overall robustness,
• They lose strength at increased 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 wet environment, especially when used outside, we recommend using encapsulated magnets, such as those made of polymer,
• Limited ability to create internal holes in the magnet – the use of a housing is recommended,
• Safety concern from tiny pieces may arise, when consumed by mistake, which is notable in the protection of children. Additionally, minuscule fragments from these magnets may disrupt scanning if inside the body,
• In cases of mass production, neodymium magnet cost may be a barrier,

Maximum holding power of the magnet – what it depends on?

The given pulling force of the magnet represents the maximum force, measured in the best circumstances, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• with vertical force applied
• under standard ambient temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is determined by in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, because even a very small distance (e.g. 0.5 mm) can cause 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 by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as fivefold. In addition, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.