MW 14x10 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose power, because even after ten years, the performance loss is only ~1% (based on calculations),
• They protect against demagnetization induced by surrounding magnetic fields remarkably well,
• In other words, due to the shiny nickel coating, the magnet obtains an aesthetic appearance,
• 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 precise design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Key role in modern technologies – they serve a purpose in data storage devices, electric motors, medical equipment or even other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in tiny dimensions, which allows for use in small systems

Disadvantages of rare earth magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to external force, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and additionally increases its overall strength,
• They lose magnetic force at extreme temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the shape and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a wet environment. For outdoor use, we recommend using sealed magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is risky,
• Possible threat from tiny pieces may arise, if ingested accidentally, which is notable in the health of young users. Additionally, miniature parts from these magnets might disrupt scanning when ingested,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

Maximum lifting capacity of the magnet – what it depends on?

The given holding capacity of the magnet means the highest holding force, determined under optimal conditions, specifically:

• 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
• in a perpendicular direction of force
• at room temperature

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

• Air gap between the magnet and the plate, as 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 determined by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under parallel forces the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.