SMZR 32x125 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain their full power for around ten years – the drop is just ~1% (based on simulations),
• They remain magnetized despite exposure to magnetic surroundings,
• In other words, due to the metallic silver coating, the magnet obtains an professional appearance,
• The outer field strength of the magnet shows remarkable magnetic properties,
• With the right combination of magnetic alloys, they reach significant thermal stability, enabling operation at or above 230°C (depending on the design),
• The ability for custom shaping or adaptation to individual needs – neodymium magnets can be manufactured in many forms and dimensions, which amplifies their functionality across industries,
• Key role in new technology industries – they are used in computer drives, electromechanical systems, medical equipment along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them ideal in compact constructions

Disadvantages of magnetic elements:

• They can break when subjected to a sudden impact. If the magnets are exposed to external force, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage while also enhances its overall resistance,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to humidity can rust. Therefore, for outdoor applications, we advise waterproof types made of coated materials,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing complex structures directly in the magnet,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is crucial in the protection of children. It should also be noted that miniature parts from these products have the potential to disrupt scanning if inside the body,
• Due to expensive raw materials, their cost is above average,

Best holding force of the magnet in ideal parameters – what contributes to it?

The given pulling force of the magnet means the maximum force, calculated in a perfect environment, specifically:

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

Lifting capacity in real conditions – factors

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

• Air gap between the magnet and the plate, since 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.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate decreases the holding force.