UMH 48x11x65 [M6] / N38 - magnetic holder with hook

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They have unchanged lifting capacity, and over nearly ten years their performance decreases symbolically – ~1% (in testing),
• They remain magnetized despite exposure to magnetic surroundings,
• The use of a decorative nickel surface provides a smooth finish,
• They have extremely strong magnetic induction on the surface of the magnet,
• Thanks to their exceptional temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• Thanks to the flexibility in shaping and the capability to adapt to specific requirements, neodymium magnets can be created in different geometries, which broadens their application range,
• Important function in new technology industries – they serve a purpose in computer drives, electric motors, healthcare devices or even technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, in miniature format,

Disadvantages of rare earth magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to shocks, we recommend in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage , and at the same time increases its overall strength,
• They lose field intensity at high temperatures. Most neodymium magnets experience permanent reduction 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,
• Magnets exposed to moisture can rust. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Limited ability to create complex details in the magnet – the use of a housing is recommended,
• Safety concern from tiny pieces may arise, if ingested accidentally, which is notable in the protection of children. Additionally, minuscule fragments from these assemblies can 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 holding power of the magnet – what affects it?

The given pulling force of the magnet corresponds to the maximum force, assessed under optimal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with zero air gap
• under perpendicular detachment force
• in normal thermal conditions

What influences lifting capacity in practice

The lifting capacity of a magnet depends on in practice key elements, according to their importance:

• 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 determined with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate reduces the lifting capacity.