SM 32x450 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their immense pulling force, neodymium magnets offer the following advantages:

• They retain their magnetic properties for nearly 10 years – the loss is just ~1% (according to analyses),
• They show superior resistance to demagnetization from outside magnetic sources,
• In other words, due to the glossy nickel coating, the magnet obtains an stylish appearance,
• 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,
• With the option for tailored forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Key role in cutting-edge sectors – they find application in HDDs, electric drives, clinical machines or even sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and additionally strengthens its overall resistance,
• Magnets lose pulling force when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of synthetic coating for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is risky,
• Possible threat from tiny pieces may arise, especially if swallowed, which is important in the family environments. It should also be noted that minuscule fragments from these devices can interfere with diagnostics if inside the body,
• Due to a complex production process, their cost is relatively high,

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given holding capacity of the magnet corresponds to the highest holding force, assessed in the best circumstances, namely:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

What influences lifting capacity in practice

Practical lifting force is determined by 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.

* Lifting capacity testing was conducted on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet and the plate reduces the lifting capacity.