SMZR 32x125 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a bright layer of gold, the element gains a modern look,
• Magnetic induction on the surface of these magnets is impressively powerful,
• 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 personalized design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Significant impact in cutting-edge sectors – they find application in hard drives, electric drives, medical equipment along with sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them ideal in small systems

Disadvantages of NdFeB magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to shocks, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and reinforces its overall strength,
• They lose strength at increased temperatures. Most neodymium magnets experience permanent reduction 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 advisable to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Potential hazard from tiny pieces may arise, especially if swallowed, which is significant in the family environments. It should also be noted that minuscule fragments from these products can interfere with diagnostics once in the system,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Detachment force of the magnet in optimal conditions – what contributes to it?

The given holding capacity of the magnet represents the highest holding force, calculated in the best circumstances, that is:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a polished side
• with zero air gap
• under perpendicular detachment force
• at room temperature

Determinants of lifting force in real conditions

Practical lifting force is dependent on factors, by priority:

• Air gap between the magnet and the plate, since 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.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the holding force.