MW 16x4 / N38 - cylindrical magnet

Advantages and disadvantages of neodymium magnets NdFeB.

Besides their durability, neodymium magnets are valued for these benefits:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• They are very resistant to demagnetization caused by external field interference,
• In other words, due to the metallic nickel coating, the magnet obtains an professional appearance,
• They exhibit superior levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to build),
• With the option for customized forming and precise design, these magnets can be produced in various shapes and sizes, greatly improving application potential,
• Wide application in advanced technical fields – they find application in computer drives, electric drives, clinical machines and technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer impressive pulling strength in compact dimensions, which makes them useful in miniature devices

Disadvantages of magnetic elements:

• They are fragile when subjected to a sudden impact. If the magnets are exposed to physical collisions, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and additionally increases its overall strength,
• They lose power at high temperatures. Most neodymium magnets experience permanent loss 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,
• Magnets exposed to moisture can oxidize. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining multi-axis shapes in neodymium magnets is risky,
• Health risk from tiny pieces may arise, when consumed by mistake, which is notable in the context of child safety. It should also be noted that small elements from these products may interfere with diagnostics if inside the body,
• Due to expensive raw materials, their cost is relatively high,

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

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

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• in conditions of no clearance
• under perpendicular detachment force
• at room temperature

Practical lifting capacity: influencing factors

The lifting capacity of a magnet is determined by in practice the following factors, according to their importance:

• Air gap between the magnet and the plate, since 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 optimal thickness, under a perpendicular pulling force, whereas under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate decreases the lifting capacity.