UMS 20x8.6x4.5x7 / N38 - conical magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their superior magnetism, neodymium magnets have these key benefits:

• They retain their attractive force for almost 10 years – the drop is just ~1% (based on simulations),
• They protect against demagnetization induced by ambient magnetic influence effectively,
• Because of the reflective layer of silver, the component looks aesthetically refined,
• The outer field strength of the magnet shows elevated magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• The ability for precise shaping and adaptation to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in advanced technical fields – they are used in hard drives, electric motors, medical equipment as well as technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which allows for use in miniature devices

Disadvantages of rare earth magnets:

• They can break when subjected to a heavy impact. If the magnets are exposed to external force, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time increases its overall durability,
• They lose power at high 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Health risk linked to microscopic shards may arise, if ingested accidentally, which is crucial in the health of young users. Moreover, small elements from these magnets might hinder health screening when ingested,
• In cases of mass production, neodymium magnet cost may not be economically viable,

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

The given strength of the magnet represents the optimal strength, measured in the best circumstances, specifically:

• 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 refined outer layer
• with no separation
• with vertical force applied
• at room temperature

Determinants of lifting force in real conditions

Practical lifting force is dependent on factors, 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 checked on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.