MPL 40x15x5 / N38 - lamellar magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their exceptional magnetic power, neodymium magnets offer the following advantages:

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (based on calculations),
• They show exceptional resistance to demagnetization from external field exposure,
• Thanks to the shiny finish and nickel coating, they have an elegant appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• With the right combination of compounds, they reach increased thermal stability, enabling operation at or above 230°C (depending on the form),
• With the option for customized forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving design adaptation,
• Key role in advanced technical fields – they find application in HDDs, electromechanical systems, medical equipment and high-tech tools,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of neodymium magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to mechanical hits, they should be placed in a steel housing. The steel housing, in the form of a holder, protects the magnet from fracture and strengthens its overall durability,
• They lose field intensity at increased temperatures. Most neodymium magnets experience permanent loss 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,
• Due to corrosion risk in humid conditions, it is recommended to use sealed magnets made of protective material for outdoor use,
• Using a cover – such as a magnetic holder – is advised due to the difficulty in manufacturing fine shapes directly in the magnet,
• Safety concern due to small fragments may arise, in case of ingestion, which is crucial in the family environments. Moreover, tiny components from these devices might hinder health screening if inside the body,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Highest magnetic holding force – what it depends on?

The given lifting capacity of the magnet corresponds to the maximum lifting force, assessed in ideal conditions, that is:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Practical lifting capacity: influencing factors

Practical lifting force is determined by elements, by priority:

• 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 was determined with the use of a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.