MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They do not lose their power approximately 10 years – the loss of strength is only ~1% (based on measurements),
• They remain magnetized despite exposure to strong external fields,
• Because of the reflective layer of gold, the component looks aesthetically refined,
• Magnetic induction on the surface of these magnets is impressively powerful,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• With the option for customized forming and targeted design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Significant impact in modern technologies – they are used in data storage devices, electromechanical systems, clinical machines or even technologically developed systems,
• Compactness – despite their small size, they generate strong force, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are fragile when subjected to a strong impact. If the magnets are exposed to physical collisions, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture while also reinforces its overall strength,
• They lose strength at high temperatures. Most neodymium magnets experience permanent decline 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 common to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining fine details in neodymium magnets is not feasible,
• Health risk linked to microscopic shards may arise, especially if swallowed, which is important in the protection of children. It should also be noted that minuscule fragments from these assemblies might hinder health screening when ingested,
• In cases of tight budgets, neodymium magnet cost may not be economically viable,

Maximum magnetic pulling force – what it depends on?

The given strength of the magnet means the optimal strength, measured in the best circumstances, namely:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a refined outer layer
• in conditions of no clearance
• with vertical force applied
• at room temperature

Key elements affecting lifting force

The lifting capacity of a magnet depends on in practice key elements, from primary to secondary:

• 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 was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate reduces the lifting capacity.