SM 32x300 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• Their strength is maintained, and after around ten years, it drops only by ~1% (theoretically),
• They are very resistant to demagnetization caused by external field interference,
• The use of a polished gold surface provides a smooth finish,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• 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 personalized design, these magnets can be produced in various shapes and sizes, greatly improving design adaptation,
• Wide application in cutting-edge sectors – they find application in computer drives, rotating machines, clinical machines along with sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, with minimal size,

Disadvantages of NdFeB magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to external force, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture while also strengthens its overall robustness,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment – during outdoor use, we recommend using waterproof magnets, such as those made of non-metallic materials,
• Limited ability to create threads in the magnet – the use of a housing is recommended,
• Possible threat due to small fragments may arise, when consumed by mistake, which is notable in the family environments. Additionally, small elements from these magnets may interfere with diagnostics after being swallowed,
• Due to expensive raw materials, their cost is considerably higher,

Maximum magnetic pulling force – what affects it?

The given strength of the magnet represents the optimal strength, calculated in the best circumstances, 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

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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 was assessed with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.