MPL 25x25x10 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• They have constant strength, and over more than 10 years their performance decreases symbolically – ~1% (in testing),
• They protect against demagnetization induced by surrounding magnetic fields effectively,
• Thanks to the shiny finish and gold coating, they have an elegant appearance,
• 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,
• The ability for custom shaping as well as adjustment to specific needs – neodymium magnets can be manufactured in many forms and dimensions, which extends the scope of their use cases,
• Wide application in new technology industries – they find application in HDDs, rotating machines, healthcare devices as well as other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They may fracture when subjected to a strong impact. If the magnets are exposed to physical collisions, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage and reinforces its overall durability,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can corrode. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is difficult,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is important in the family environments. Moreover, miniature parts from these assemblies can hinder health screening if inside the body,
• Due to the price of neodymium, their cost is relatively high,

Detachment force of the magnet in optimal conditions – what affects it?

The given strength of the magnet represents the optimal strength, measured in ideal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• in normal thermal conditions

Determinants of lifting force in real conditions

Practical lifting force is dependent on elements, by priority:

• 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 was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate decreases the lifting capacity.