MPL 20x8x4 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They retain their full power for almost ten years – the drop is just ~1% (according to analyses),
• They show superior resistance to demagnetization from outside magnetic sources,
• In other words, due to the shiny nickel coating, the magnet obtains an professional appearance,
• Magnetic induction on the surface of these magnets is very strong,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for precise shaping and adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Significant impact in cutting-edge sectors – they find application in data storage devices, electric motors, clinical machines as well as other advanced devices,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from breakage and additionally strengthens its overall durability,
• High temperatures may significantly reduce the strength of neodymium magnets. Typically, above 80°C, they experience permanent deterioration in performance (depending on height). 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,
• They rust in a wet environment, especially when used outside, we recommend using moisture-resistant magnets, such as those made of plastic,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Possible threat from tiny pieces may arise, if ingested accidentally, which is notable in the context of child safety. Additionally, tiny components from these devices can complicate medical imaging after being swallowed,
• High unit cost – neodymium magnets are costlier than other types of magnets (e.g., ferrite), which increases the cost of large-scale applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The given lifting capacity of the magnet means the maximum lifting force, calculated in ideal conditions, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet depends on in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) causes 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 polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.