UMGZ 20x15x7 [M4] GZ / N38 - magnetic holder external thread

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their exceptional strength, neodymium magnets offer the following advantages:

• They do not lose their power approximately ten years – the decrease of lifting capacity is only ~1% (theoretically),
• They show superior resistance to demagnetization from outside magnetic sources,
• The use of a decorative silver surface provides a eye-catching finish,
• They have exceptional magnetic induction on the surface of the magnet,
• Thanks to their high temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• Thanks to the freedom in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in diverse shapes and sizes, which expands their usage potential,
• Important function in new technology industries – they are used in HDDs, electromechanical systems, medical equipment along with high-tech tools,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks and additionally enhances its overall strength,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can corrode. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is notable in the context of child safety. It should also be noted that small elements from these products have the potential to interfere with diagnostics once in the system,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Maximum magnetic pulling force – what it depends on?

The given holding capacity of the magnet represents the highest holding force, calculated in ideal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

In practice, the holding capacity of a magnet is conditioned by these factors, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, since 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 testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under shearing force the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.