UMGGZ 66x8.5 [M8] GZ / N38 - rubber magnetic holder external thread

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They do not lose their magnetism, even after nearly ten years – the loss of lifting capacity is only ~1% (based on measurements),
• They remain magnetized despite exposure to magnetic surroundings,
• By applying a bright layer of silver, the element gains a clean look,
• They possess significant 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,
• Thanks to the possibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in various configurations, which expands their application range,
• Important function in advanced technical fields – they are utilized in HDDs, rotating machines, clinical machines and technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, in miniature format,

Disadvantages of neodymium magnets:

• They may fracture when subjected to a powerful impact. If the magnets are exposed to external force, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally strengthens its overall robustness,
• High temperatures may significantly reduce the field efficiency of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on height). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we recommend waterproof types made of coated materials,
• Limited ability to create internal holes in the magnet – the use of a mechanical support is recommended,
• Potential hazard related to magnet particles may arise, especially if swallowed, which is significant in the family environments. Moreover, tiny components from these devices may complicate medical imaging if inside the body,
• Due to the price of neodymium, their cost is relatively high,

Detachment force of the magnet in optimal conditions – what affects it?

The given strength of the magnet represents the optimal strength, calculated in ideal conditions, namely:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a polished side
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Determinants of practical lifting force of a magnet

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, because 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.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.