MPL 15x2x30 / 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 remains stable, and after approximately ten years, it drops only by ~1% (theoretically),
• Their ability to resist magnetic interference from external fields is impressive,
• By applying a reflective layer of nickel, the element gains a sleek look,
• They have very high magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the flexibility in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which increases their application range,
• Key role in cutting-edge sectors – they are used in HDDs, electric drives, medical equipment and other advanced devices,
• Thanks to their power density, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to mechanical hits, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks while also reinforces its overall robustness,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment. If exposed to rain, we recommend using sealed magnets, such as those made of non-metallic materials,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is restricted,
• Safety concern linked to microscopic shards may arise, when consumed by mistake, which is significant in the health of young users. Additionally, small elements from these assemblies can hinder health screening if inside the body,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The given holding capacity of the magnet represents the highest holding 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 polished side
• in conditions of no clearance
• with vertical force applied
• at room temperature

Practical aspects of lifting capacity – 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, 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the lifting capacity.