SM 32x225 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their strength remains stable, and after approximately ten years, it drops only by ~1% (according to research),
• They remain magnetized despite exposure to magnetic noise,
• Because of the lustrous layer of gold, the component looks high-end,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the design),
• With the option for customized forming and precise design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
• Important function in cutting-edge sectors – they are used in data storage devices, electric drives, clinical machines as well as other advanced devices,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They may fracture when subjected to a sudden impact. If the magnets are exposed to mechanical hits, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks while also strengthens its overall strength,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment, especially when used outside, we recommend using waterproof magnets, such as those made of polymer,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Health risk related to magnet particles may arise, when consumed by mistake, which is crucial in the protection of children. It should also be noted that tiny components from these assemblies have the potential to interfere with diagnostics after being swallowed,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which may limit large-scale applications

Optimal lifting capacity of a neodymium magnet – what affects it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, assessed in a perfect environment, namely:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a polished side
• with zero air gap
• under perpendicular detachment force
• under standard ambient temperature

Determinants of practical lifting force of a magnet

The lifting capacity of a magnet is determined by in practice the following factors, ordered from most important to least 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 was measured using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.