MPL 40x40x15 / N38 - lamellar magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after 10 years, the decline in efficiency is only ~1% (in laboratory conditions),
• They protect against demagnetization induced by ambient electromagnetic environments effectively,
• Thanks to the glossy finish and silver coating, they have an elegant appearance,
• They possess significant magnetic force measurable at the magnet’s surface,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for accurate shaping and adjustment to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Significant impact in modern technologies – they find application in computer drives, electric motors, healthcare devices along with high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which allows for use in miniature devices

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to external force, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time enhances its overall robustness,
• They lose power at high temperatures. Most neodymium magnets experience permanent loss in strength when heated above 80°C (depending on the dimensions 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 recommended to use sealed magnets made of plastic for outdoor use,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is risky,
• Safety concern related to magnet particles may arise, in case of ingestion, which is notable in the health of young users. Furthermore, small elements from these devices have the potential to interfere with diagnostics once in the system,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Highest magnetic holding force – what it depends on?

The given strength of the magnet represents the optimal strength, measured in the best circumstances, that is:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• of a thickness of at least 10 mm
• with a refined outer layer
• in conditions of no clearance
• in a perpendicular direction of force
• under standard ambient temperature

Practical lifting capacity: influencing factors

In practice, the holding capacity of a magnet is affected by the following aspects, in descending order of importance:

• Air gap between the magnet and the plate, since 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 testing was conducted on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.