SM 32x200 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their full power for nearly ten years – the loss is just ~1% (in theory),
• They show strong resistance to demagnetization from external magnetic fields,
• Thanks to the shiny finish and gold coating, they have an visually attractive appearance,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• With the right combination of materials, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the structure),
• With the option for tailored forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Significant impact in modern technologies – they find application in data storage devices, rotating machines, diagnostic apparatus and high-tech tools,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They can break when subjected to a powerful impact. If the magnets are exposed to shocks, it is suggested to place them in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and additionally enhances its overall strength,
• Magnets lose field strength 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 wise to use sealed magnets made of rubber for outdoor use,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is not feasible,
• Possible threat due to small fragments may arise, especially if swallowed, which is significant in the context of child safety. It should also be noted that small elements from these magnets may interfere with diagnostics if inside the body,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Maximum lifting force for a neodymium magnet – what affects it?

The given strength of the magnet corresponds to the optimal strength, assessed in ideal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• in a perpendicular direction of force
• at room temperature

Magnet lifting force in use – key factors

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

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause 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 was determined by applying a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the load capacity is reduced by as much as 75%. Moreover, even a slight gap {between} the magnet and the plate decreases the load capacity.