UMS 75x19x10.5x18 / N38 - conical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have constant strength, and over more than 10 years their attraction force decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic noise,
• Because of the lustrous layer of silver, the component looks high-end,
• They have exceptional magnetic induction on the surface of the magnet,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which expands their application range,
• Significant impact in new technology industries – they serve a purpose in HDDs, electromechanical systems, clinical machines or even sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which allows for use in miniature devices

Disadvantages of neodymium magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to shocks, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks and additionally increases 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 dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of protective material for outdoor use,
• Limited ability to create internal holes in the magnet – the use of a housing is recommended,
• Potential hazard from tiny pieces may arise, especially if swallowed, which is crucial in the family environments. Additionally, small elements from these magnets can complicate medical imaging when ingested,
• In cases of mass production, neodymium magnet cost may be a barrier,

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

The given strength of the magnet means the optimal strength, calculated under optimal conditions, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• in normal thermal conditions

Key elements affecting lifting force

The lifting capacity of a magnet depends on in practice the following factors, 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 was measured using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the load capacity.