UMS 16x6.5x3.5x5 / N38 - conical magnetic holder

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• Their strength remains stable, and after around 10 years, it drops only by ~1% (according to research),
• They remain magnetized despite exposure to strong external fields,
• Because of the reflective layer of silver, the component looks aesthetically refined,
• The outer field strength of the magnet shows advanced magnetic properties,
• 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 individual requirements, neodymium magnets can be created in different geometries, which increases their functional possibilities,
• Significant impact in advanced technical fields – they find application in data storage devices, electric motors, clinical machines along with other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, it is advisable to use in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks and additionally strengthens its overall strength,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent weakening 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 damp air can corrode. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Limited ability to create precision features in the magnet – the use of a mechanical support is recommended,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is crucial in the context of child safety. Additionally, small elements from these products can interfere with diagnostics after being swallowed,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Maximum lifting capacity of the magnet – what affects it?

The given pulling force of the magnet means the maximum force, measured under optimal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a refined outer layer
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Determinants of practical lifting force of a magnet

In practice, the holding capacity of a magnet is conditioned by the following aspects, from crucial to less important:

• 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.

* Lifting capacity testing was conducted on a smooth plate of suitable thickness, under perpendicular forces, in contrast under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.