MPL 50x50x10 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous strength, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after ten years, the decline in efficiency is only ~1% (according to literature),
• They are highly resistant to demagnetization caused by external magnetic fields,
• In other words, due to the metallic nickel coating, the magnet obtains an professional appearance,
• Magnetic induction on the surface of these magnets is notably high,
• Thanks to their high temperature resistance, they can operate (depending on the geometry) even at temperatures up to 230°C or more,
• The ability for accurate shaping as well as adaptation to specific needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which enhances their versatility in applications,
• Key role in cutting-edge sectors – they are utilized in HDDs, rotating machines, clinical machines along with technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in small dimensions, which makes them ideal in miniature devices

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, they should be placed in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and additionally reinforces its overall durability,
• They lose power at elevated 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 advisable to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is restricted,
• Safety concern related to magnet particles may arise, if ingested accidentally, which is notable in the health of young users. Furthermore, minuscule fragments from these assemblies have the potential to hinder health screening if inside the body,
• Due to the price of neodymium, their cost is considerably higher,

Best holding force of the magnet in ideal parameters – what it depends on?

The given holding capacity of the magnet means the highest holding force, measured in ideal conditions, specifically:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• at room temperature

Key elements affecting lifting force

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

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