UMGW 20x15x7 [M4] GW / N38 - magnetic holder internal thread

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain their full power for around 10 years – the loss is just ~1% (in theory),
• They remain magnetized despite exposure to strong external fields,
• The use of a mirror-like nickel surface provides a eye-catching finish,
• Magnetic induction on the surface of these magnets is notably high,
• With the right combination of materials, they reach increased thermal stability, enabling operation at or above 230°C (depending on the design),
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in various configurations, which increases their functional possibilities,
• Significant impact in advanced technical fields – they serve a purpose in HDDs, electric motors, diagnostic apparatus and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which allows for use in small systems

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks while also reinforces its overall durability,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (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,
• Magnets exposed to wet conditions can oxidize. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Using a cover – such as a magnetic holder – is advised due to the limitations in manufacturing holes directly in the magnet,
• Potential hazard due to small fragments may arise, especially if swallowed, which is notable in the protection of children. It should also be noted that small elements from these assemblies can hinder health screening when ingested,
• Due to a complex production process, their cost is relatively high,

Highest magnetic holding force – what it depends on?

The given holding capacity of the magnet means the highest holding force, measured in the best circumstances, specifically:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• under standard ambient temperature

Key elements affecting lifting force

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, as 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.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.