MW 5x15 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their strength remains stable, and after approximately 10 years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by external electromagnetic environments very well,
• By applying a shiny layer of silver, the element gains a modern look,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for tailored forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Significant impact in modern technologies – they are used in hard drives, electric drives, healthcare devices or even sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in compact dimensions, which makes them useful in miniature devices

Disadvantages of neodymium magnets:

• They are fragile when subjected to a sudden 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 cracks and enhances its overall robustness,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a moist environment. For outdoor use, we recommend using moisture-resistant magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is risky,
• Potential hazard due to small fragments may arise, in case of ingestion, which is crucial in the family environments. It should also be noted that small elements from these assemblies have the potential to disrupt scanning if inside the body,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Magnetic strength at its maximum – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, determined in the best circumstances, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• under standard ambient temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet depends on in practice key elements, ordered from most important to least significant:

• 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 testing was conducted on plates with a smooth surface of suitable thickness, under perpendicular forces, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.