AM Haczyk M4 - magnetic accessories

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• Their strength is maintained, and after approximately ten years, it drops only by ~1% (according to research),
• They are very resistant to demagnetization caused by external magnetic fields,
• In other words, due to the shiny silver coating, the magnet obtains an aesthetic appearance,
• Magnetic induction on the surface of these magnets is impressively powerful,
• Thanks to their high temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C or more,
• Thanks to the possibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which broadens their application range,
• Important function in modern technologies – they serve a purpose in hard drives, rotating machines, clinical machines or even sophisticated instruments,
• Compactness – despite their small size, they provide high effectiveness, making them ideal for precision applications

Disadvantages of rare earth magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to shocks, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from breakage and reinforces its overall robustness,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on form). To prevent this, we offer heat-resistant magnets marked [AH], capable of working up to 230°C, which makes them perfect for high-temperature use,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of synthetic coating for outdoor use,
• Limited ability to create precision features in the magnet – the use of a housing is recommended,
• Potential hazard due to small fragments may arise, if ingested accidentally, which is significant in the family environments. Additionally, tiny components from these assemblies have the potential to interfere with diagnostics if inside the body,
• In cases of mass production, neodymium magnet cost is a challenge,

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

The given lifting capacity of the magnet means the maximum lifting force, measured 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 refined outer layer
• with no separation
• in a perpendicular direction of force
• at room temperature

Magnet lifting force in use – key factors

The lifting capacity of a magnet is determined by in practice the following factors, from primary to secondary:

• 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.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.