MW 40x15 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets NdFeB.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They do not lose their even during around 10 years – the decrease of strength is only ~1% (theoretically),
• They protect against demagnetization induced by surrounding electromagnetic environments effectively,
• By applying a shiny layer of silver, the element gains a clean look,
• Magnetic induction on the surface of these magnets is notably high,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for fine forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Significant impact in new technology industries – they are utilized in HDDs, rotating machines, healthcare devices and technologically developed systems,
• Thanks to their power density, small magnets offer high magnetic performance, in miniature format,

Disadvantages of magnetic elements:

• They can break when subjected to a sudden impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and increases its overall robustness,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s profile). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is advisable to use sealed magnets made of rubber for outdoor use,
• Limited ability to create complex details in the magnet – the use of a mechanical support is recommended,
• Safety concern due to small fragments may arise, when consumed by mistake, which is notable in the family environments. It should also be noted that small elements from these magnets can disrupt scanning after being swallowed,
• Due to a complex production process, their cost is relatively high,

Highest magnetic holding force – what affects it?

The given pulling force of the magnet represents the maximum force, calculated under optimal conditions, specifically:

• with mild steel, serving as a magnetic flux conductor
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• in a perpendicular direction of force
• in normal thermal conditions

Practical aspects of lifting capacity – factors

Practical lifting force is determined by factors, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, as 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 carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate reduces the holding force.