JM 15x40 - jajka w pudełku/cena za parę - magnetic eggs

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They have unchanged lifting capacity, and over nearly ten years their attraction force decreases symbolically – ~1% (in testing),
• They protect against demagnetization induced by ambient magnetic influence remarkably well,
• In other words, due to the glossy gold coating, the magnet obtains an professional appearance,
• Magnetic induction on the surface of these magnets is impressively powerful,
• 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 fine forming and precise design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
• Wide application in new technology industries – they are used in HDDs, electromechanical systems, clinical machines or even sophisticated instruments,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of magnetic elements:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from damage while also reinforces its overall strength,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of protective material for outdoor use,
• Limited ability to create threads in the magnet – the use of a mechanical support is recommended,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is significant in the protection of children. Furthermore, small elements from these assemblies can complicate medical imaging if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The given holding capacity of the magnet represents the highest holding force, determined in ideal conditions, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• having a thickness of no less than 10 millimeters
• with a polished side
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Practical lifting capacity: influencing 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, 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 was assessed using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate reduces the load capacity.