SM 25x275 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable power, neodymium magnets have these key benefits:

• They have unchanged lifting capacity, and over more than ten years their performance decreases symbolically – ~1% (according to theory),
• They protect against demagnetization induced by surrounding electromagnetic environments effectively,
• In other words, due to the shiny silver coating, the magnet obtains an stylish appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of compounds, they reach significant thermal stability, enabling operation at or above 230°C (depending on the structure),
• The ability for precise shaping and adjustment to individual needs – neodymium magnets can be manufactured in multiple variants of geometries, which amplifies their functionality across industries,
• Key role in cutting-edge sectors – they are used in computer drives, electromechanical systems, healthcare devices along with technologically developed systems,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to physical collisions, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks while also reinforces its overall robustness,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can corrode. Therefore, for outdoor applications, we suggest waterproof types made of plastic,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is difficult,
• Safety concern from tiny pieces may arise, in case of ingestion, which is significant in the health of young users. Furthermore, small elements from these devices may disrupt scanning if inside the body,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

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, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• with zero air gap
• under perpendicular detachment force
• at room temperature

Lifting capacity in practice – influencing factors

Practical lifting force is dependent on factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, because 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 testing was performed on a smooth plate of optimal thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.