MW 29x10 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

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

• They retain their magnetic properties for almost ten years – the loss is just ~1% (according to analyses),
• They remain magnetized despite exposure to magnetic noise,
• By applying a reflective layer of nickel, the element gains a modern look,
• They possess significant magnetic force measurable at the magnet’s surface,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the shape),
• The ability for accurate shaping and adaptation to custom needs – neodymium magnets can be manufactured in multiple variants of geometries, which extends the scope of their use cases,
• Wide application in modern technologies – they are used in computer drives, electromechanical systems, healthcare devices as well as other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them useful in miniature devices

Disadvantages of NdFeB magnets:

• They may fracture 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 damage and additionally increases its overall durability,
• They lose field intensity at extreme 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,
• They rust in a wet environment. If exposed to rain, we recommend using waterproof magnets, such as those made of non-metallic materials,
• Using a cover – such as a magnetic holder – is advised due to the restrictions in manufacturing complex structures directly in the magnet,
• Safety concern from tiny pieces may arise, in case of ingestion, which is significant in the context of child safety. Additionally, minuscule fragments from these products might complicate medical imaging once in the system,
• High unit cost – neodymium magnets are pricier than other types of magnets (e.g., ferrite), which can restrict large-scale applications

Best holding force of the magnet in ideal parameters – what it depends on?

The given lifting capacity of the magnet means the maximum lifting force, determined in a perfect environment, namely:

• with mild steel, serving as a magnetic flux conductor
• having a thickness of no less than 10 millimeters
• with a smooth surface
• with no separation
• under perpendicular detachment force
• under standard ambient temperature

Lifting capacity in real conditions – factors

Practical lifting force is dependent on 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 was assessed with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, however under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.