MW 16x3 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They retain their attractive force for nearly ten years – the loss is just ~1% (according to analyses),
• Their ability to resist magnetic interference from external fields is impressive,
• In other words, due to the shiny gold coating, the magnet obtains an aesthetic appearance,
• 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,
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in various configurations, which increases their functional possibilities,
• Significant impact in advanced technical fields – they are utilized in computer drives, electric motors, clinical machines along with high-tech tools,
• 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 powerful impact. If the magnets are exposed to shocks, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time enhances its overall durability,
• They lose strength at increased 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 recommended to use sealed magnets made of protective material for outdoor use,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is restricted,
• Safety concern from tiny pieces may arise, especially if swallowed, which is notable in the context of child safety. Moreover, tiny components from these assemblies may disrupt scanning after being swallowed,
• Due to a complex production process, their cost is relatively high,

Detachment force of the magnet in optimal conditions – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, assessed under optimal conditions, namely:

• with the use of low-carbon steel plate acting as a magnetic yoke
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• with vertical force applied
• at room temperature

Impact of factors on magnetic holding capacity in practice

Practical lifting force is dependent on factors, by priority:

• 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 assessed using a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet and the plate decreases the load capacity.