MPL 15x2x30 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• Their strength remains stable, and after around ten years, it drops only by ~1% (theoretically),
• Their ability to resist magnetic interference from external fields is among the best,
• The use of a mirror-like gold surface provides a refined finish,
• They have extremely strong magnetic induction on the surface of the magnet,
• Thanks to their exceptional temperature resistance, they can operate (depending on the form) 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 application potential,
• Significant impact in advanced technical fields – they are utilized in computer drives, rotating machines, medical equipment or even sophisticated instruments,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to shocks, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage and reinforces its overall strength,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (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 humidity can degrade. Therefore, for outdoor applications, we advise waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is important in the context of child safety. Moreover, small elements from these magnets have the potential to disrupt scanning when ingested,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

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

The given pulling force of the magnet represents the maximum force, assessed in the best circumstances, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

In practice, the holding capacity of a magnet is conditioned by these factors, in descending order of importance:

• 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.