MW 38x3.5 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

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

• They virtually do not lose strength, because even after ten years, the decline in efficiency is only ~1% (in laboratory conditions),
• They protect against demagnetization induced by surrounding magnetic fields remarkably well,
• In other words, due to the shiny nickel coating, the magnet obtains an professional appearance,
• The outer field strength of the magnet shows elevated magnetic properties,
• 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 geometry),
• With the option for customized forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Key role in cutting-edge sectors – they are used in HDDs, electromechanical systems, healthcare devices and sophisticated instruments,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to mechanical hits, it is suggested to place them in a protective case. The steel housing, in the form of a holder, protects the magnet from cracks while also enhances its overall resistance,
• Magnets lose magnetic efficiency when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s form). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a humid environment. For outdoor use, we recommend using sealed magnets, such as those made of non-metallic materials,
• Limited ability to create threads in the magnet – the use of a magnetic holder is recommended,
• Health risk linked to microscopic shards may arise, when consumed by mistake, which is crucial in the health of young users. Moreover, tiny components from these products have the potential to disrupt scanning if inside the body,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

Maximum holding power of the magnet – what it depends on?

The given holding capacity of the magnet represents the highest holding force, assessed under optimal conditions, that is:

• with mild steel, used as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a refined outer layer
• with zero air gap
• under perpendicular detachment force
• at room temperature

Practical aspects of lifting capacity – factors

The lifting capacity of a magnet is determined by in practice the following factors, ordered from most important to least significant:

• Air gap between the magnet and the plate, because 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 testing was performed on a smooth plate of suitable thickness, under perpendicular forces, however under shearing force the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.