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

Advantages and disadvantages of neodymium magnets NdFeB.

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

• 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 polished nickel surface provides a smooth finish,
• They have very high magnetic induction on the surface of the magnet,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• With the option for customized forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Important function in new technology industries – they find application in computer drives, rotating machines, medical equipment along with technologically developed systems,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from damage while also increases its overall resistance,
• High temperatures may significantly reduce the holding force of neodymium magnets. Typically, above 80°C, they experience permanent loss in performance (depending on form). 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 rust. Therefore, for outdoor applications, we suggest waterproof types made of non-metallic composites,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Potential hazard linked to microscopic shards may arise, in case of ingestion, which is notable in the health of young users. It should also be noted that tiny components from these devices have the potential to interfere with diagnostics once in the system,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Highest magnetic holding force – what it depends on?

The given lifting capacity of the magnet represents the maximum lifting force, calculated in the best circumstances, namely:

• with mild steel, used as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• under perpendicular detachment force
• at room temperature

Impact of factors on magnetic holding capacity in practice

The lifting capacity of a magnet is influenced by in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, as 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 performed on a smooth plate of suitable thickness, under perpendicular forces, in contrast under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate reduces the load capacity.