WM 34.5x24.3x17 / N38 - magnetic hanger

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their strength approximately ten years – the decrease of lifting capacity is only ~1% (theoretically),
• They show exceptional resistance to demagnetization from external magnetic fields,
• Thanks to the polished finish and gold coating, they have an visually attractive appearance,
• They possess intense magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for custom shaping and adjustment to custom needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Wide application in new technology industries – they are used in computer drives, rotating machines, diagnostic apparatus along with other advanced devices,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time strengthens its overall durability,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent loss 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,
• They rust in a wet environment. For outdoor use, we recommend using waterproof magnets, such as those made of plastic,
• Limited ability to create internal holes in the magnet – the use of a magnetic holder is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is crucial in the protection of children. It should also be noted that miniature parts from these devices have the potential to complicate medical imaging if inside the body,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Breakaway strength of the magnet in ideal conditions – what it depends on?

The given holding capacity of the magnet means the highest holding force, calculated in ideal conditions, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• under standard ambient temperature

Key elements affecting lifting force

The lifting capacity of a magnet is determined by in practice the following factors, ordered from most important to least 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.

* Lifting capacity was measured with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the load capacity is reduced by as much as 5 times. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.