UMS 32x10.5x5.5x8 / N38 - conical magnetic holder

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their magnetic field remains stable, and after around ten years, it drops only by ~1% (theoretically),
• They protect against demagnetization induced by surrounding magnetic influence remarkably well,
• The use of a decorative nickel surface provides a eye-catching finish,
• The outer field strength of the magnet shows remarkable magnetic properties,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for customized forming and targeted design, these magnets can be produced in multiple shapes and sizes, greatly improving engineering flexibility,
• Significant impact in new technology industries – they serve a purpose in computer drives, electric drives, medical equipment along with sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them ideal in miniature devices

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to mechanical hits, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture , and at the same time enhances its overall resistance,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration 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,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is difficult,
• Possible threat related to magnet particles may arise, in case of ingestion, which is notable in the protection of children. It should also be noted that small elements from these devices can interfere with diagnostics if inside the body,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

Highest magnetic holding force – what affects it?

The given strength of the magnet represents the optimal strength, determined in ideal 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 polished side
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Lifting capacity in real conditions – factors

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• 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 carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 75%. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.