MW 14x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their superior power, neodymium magnets have these key benefits:

• They virtually do not lose power, because even after 10 years, the decline in efficiency is only ~1% (in laboratory conditions),
• They remain magnetized despite exposure to magnetic noise,
• Because of the reflective layer of nickel, the component looks high-end,
• They possess intense magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for exceptionally strong magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• Thanks to the freedom in shaping and the capability to adapt to individual requirements, neodymium magnets can be created in diverse shapes and sizes, which broadens their functional possibilities,
• Significant impact in new technology industries – they are utilized in data storage devices, electromechanical systems, medical equipment as well as high-tech tools,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in small dimensions, which allows for use in compact constructions

Disadvantages of rare earth magnets:

• They are fragile when subjected to a heavy 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 while also reinforces its overall resistance,
• They lose strength at extreme temperatures. Most neodymium magnets experience permanent decline in strength when heated above 80°C (depending on the shape 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 common to use sealed magnets made of plastic for outdoor use,
• Limited ability to create complex details in the magnet – the use of a housing is recommended,
• Possible threat linked to microscopic shards may arise, in case of ingestion, which is notable in the context of child safety. It should also be noted that miniature parts from these devices might disrupt scanning if inside the body,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Highest magnetic holding force – what it depends on?

The given pulling force of the magnet corresponds to the maximum force, determined under optimal conditions, that is:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• at room temperature

Practical aspects of lifting capacity – factors

Practical lifting force is determined by elements, by priority:

• 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, in contrast under shearing force the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the holding force.