MPL 40x18x10 SH / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They do not lose their power around ten years – the decrease of power is only ~1% (theoretically),
• They show superior resistance to demagnetization from external field exposure,
• The use of a mirror-like gold surface provides a refined finish,
• 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 specific requirements, neodymium magnets can be created in different geometries, which increases their application range,
• Wide application in new technology industries – they find application in HDDs, electric motors, healthcare devices and high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer intense magnetic field in small dimensions, which makes them useful in compact constructions

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from damage , and at the same time increases its overall durability,
• They lose power at elevated temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to moisture can degrade. Therefore, for outdoor applications, we suggest waterproof types made of coated materials,
• Limited ability to create internal holes in the magnet – the use of a housing is recommended,
• Health risk from tiny pieces may arise, if ingested accidentally, which is notable in the context of child safety. Moreover, minuscule fragments from these devices might hinder health screening after being swallowed,
• High unit cost – neodymium magnets are more expensive than other types of magnets (e.g., ferrite), which may limit large-scale applications

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

The given lifting capacity of the magnet means the maximum lifting force, determined in ideal conditions, that is:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a smooth surface
• with no separation
• in a perpendicular direction of force
• under standard ambient temperature

Determinants of lifting force in real conditions

The lifting capacity of a magnet is determined by in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, because 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.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.