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

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They do not lose their magnetism, even after nearly 10 years – the decrease of lifting capacity is only ~1% (according to tests),
• They remain magnetized despite exposure to magnetic surroundings,
• The use of a decorative gold surface provides a refined finish,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• Thanks to their enhanced temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• With the option for fine forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Wide application in modern technologies – they are utilized in HDDs, rotating machines, diagnostic apparatus as well as sophisticated instruments,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall durability,
• They lose magnetic force at increased temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we recommend waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is restricted,
• Potential hazard linked to microscopic shards may arise, when consumed by mistake, which is significant in the health of young users. It should also be noted that miniature parts from these devices can disrupt scanning after being swallowed,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Best holding force of the magnet in ideal parameters – what affects it?

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

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• at room temperature

What influences lifting capacity in practice

The lifting capacity of a magnet depends on in practice the following factors, ordered from most important to least significant:

• 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 conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.