SMZR 25x250 / N52 - magnetic separator with handle

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after 10 years, the performance loss is only ~1% (based on calculations),
• They show superior resistance to demagnetization from outside magnetic sources,
• Because of the reflective layer of gold, the component looks visually appealing,
• Magnetic induction on the surface of these magnets is impressively powerful,
• Thanks to their high temperature resistance, they can operate (depending on the form) even at temperatures up to 230°C or more,
• With the option for customized forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving design adaptation,
• Key role in advanced technical fields – they are utilized in computer drives, rotating machines, clinical machines as well as high-tech tools,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are fragile when subjected to a heavy impact. If the magnets are exposed to external force, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from damage and reinforces its overall durability,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible performance loss (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a damp environment. For outdoor use, we recommend using sealed magnets, such as those made of polymer,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Health risk related to magnet particles may arise, when consumed by mistake, which is important in the protection of children. Moreover, tiny components from these assemblies may hinder health screening when ingested,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given strength of the magnet corresponds to the optimal strength, determined in ideal conditions, namely:

• 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 refined outer layer
• with no separation
• in a perpendicular direction of force
• at room temperature

Magnet lifting force in use – key factors

In practice, the holding capacity of a magnet is conditioned by the following aspects, arranged from the most important to the least relevant:

• 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 was measured with the use of a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.