MPL 15x15x5 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Apart from their notable holding force, neodymium magnets have these key benefits:

• They virtually do not lose strength, because even after 10 years, the decline in efficiency is only ~1% (in laboratory conditions),
• Their ability to resist magnetic interference from external fields is notable,
• By applying a shiny layer of silver, the element gains a modern look,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of compounds, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the structure),
• With the option for fine forming and personalized design, these magnets can be produced in various shapes and sizes, greatly improving engineering flexibility,
• Significant impact in cutting-edge sectors – they find application in computer drives, electric motors, medical equipment and sophisticated instruments,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of magnetic elements:

• They can break when subjected to a sudden 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 cracks and additionally enhances its overall resistance,
• They lose field intensity at extreme temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the form and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can corrode. Therefore, for outdoor applications, it's best to use waterproof types made of non-metallic composites,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is restricted,
• Health risk related to magnet particles may arise, when consumed by mistake, which is crucial in the health of young users. Furthermore, minuscule fragments from these devices can complicate medical imaging if inside the body,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

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

The given pulling force of the magnet corresponds to the maximum force, calculated in the best circumstances, that is:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• in a perpendicular direction of force
• at room temperature

Key elements affecting lifting force

The lifting capacity of a magnet is determined by in practice the following factors, from primary to secondary:

• 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.

* Holding force was checked on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, whereas under parallel forces the load capacity is reduced by as much as fivefold. In addition, even a slight gap {between} the magnet and the plate decreases the lifting capacity.