MPL 40x18x10 SH / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their magnetic field is maintained, and after approximately ten years, it drops only by ~1% (theoretically),
• Their ability to resist magnetic interference from external fields is among the best,
• Because of the reflective layer of nickel, the component looks high-end,
• Magnetic induction on the surface of these magnets is very strong,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and personalized design, these magnets can be produced in numerous shapes and sizes, greatly improving engineering flexibility,
• Key role in advanced technical fields – they are used in HDDs, electric motors, diagnostic apparatus along with sophisticated instruments,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in tiny dimensions, which makes them useful in small systems

Disadvantages of NdFeB magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, they should be placed in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time increases its overall strength,
• They lose magnetic force at increased 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,
• Due to corrosion risk in humid conditions, it is wise to use sealed magnets made of rubber for outdoor use,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is risky,
• Potential hazard from tiny pieces may arise, in case of ingestion, which is important in the protection of children. It should also be noted that small elements from these assemblies may complicate medical imaging after being swallowed,
• Higher purchase price is an important factor to consider compared to ceramic magnets, especially in budget-sensitive applications

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

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

• 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 polished side
• in conditions of no clearance
• with vertical force applied
• under standard ambient temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by these factors, from crucial to less important:

• 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 measured using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under parallel forces the holding force is lower. In addition, even a slight gap {between} the magnet and the plate decreases the holding force.