MW 5x2 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent magnetism, neodymium magnets have these key benefits:

• They retain their full power for around 10 years – the drop is just ~1% (based on simulations),
• Their ability to resist magnetic interference from external fields is impressive,
• Thanks to the polished finish and gold coating, they have an aesthetic appearance,
• They possess strong magnetic force measurable at the magnet’s surface,
• Thanks to their exceptional temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in different geometries, which expands their usage potential,
• Important function in modern technologies – they are utilized in data storage devices, electric drives, clinical machines along with technologically developed systems,
• 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 physical collisions, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from fracture and reinforces its overall durability,
• They lose power at extreme temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the shape 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,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is restricted,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is significant in the context of child safety. It should also be noted that small elements from these magnets have the potential to hinder health screening once in the system,
• In cases of mass production, neodymium magnet cost may be a barrier,

Detachment force of the magnet in optimal conditions – what affects it?

The given holding capacity of the magnet corresponds to the highest holding force, assessed in the best circumstances, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• under perpendicular detachment force
• at room temperature

Key elements affecting lifting force

Practical lifting force is dependent on factors, 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.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.