MPL 30x20x4 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose their magnetism, even after approximately 10 years – the loss of strength is only ~1% (based on measurements),
• They remain magnetized despite exposure to magnetic noise,
• By applying a shiny layer of nickel, the element gains a clean look,
• They possess significant magnetic force measurable at the magnet’s surface,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for tailored forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Wide application in new technology industries – they are used in HDDs, electromechanical systems, medical equipment along with other advanced devices,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall robustness,
• They lose magnetic force at high temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to humidity can rust. Therefore, for outdoor applications, we advise waterproof types made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing threads directly in the magnet,
• Health risk linked to microscopic shards may arise, in case of ingestion, which is crucial in the family environments. Moreover, miniature parts from these devices may hinder health screening after being swallowed,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Maximum holding power of the magnet – what affects it?

The given holding capacity of the magnet means the highest holding force, calculated under optimal conditions, namely:

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

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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 testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, however under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the load capacity.