SMZR 25x225 / N52 - magnetic separator with handle

Advantages and disadvantages of neodymium magnets NdFeB.

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

• Their strength is durable, and after around ten years, it drops only by ~1% (according to research),
• They show strong resistance to demagnetization from outside magnetic sources,
• By applying a shiny layer of silver, the element gains a clean look,
• They exhibit elevated levels of magnetic induction near the outer area of the magnet,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to form),
• Thanks to the flexibility in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which expands their functional possibilities,
• Wide application in modern technologies – they are utilized in computer drives, electric motors, medical equipment along with sophisticated instruments,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of rare earth magnets:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to physical collisions, we recommend in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks , and at the same time strengthens its overall resistance,
• They lose field intensity at elevated temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the geometry and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a damp environment. If exposed to rain, we recommend using encapsulated magnets, such as those made of rubber,
• The use of a protective casing or external holder is recommended, since machining internal cuts in neodymium magnets is difficult,
• Potential hazard from tiny pieces may arise, especially if swallowed, which is significant in the family environments. Furthermore, minuscule fragments from these products may disrupt scanning if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Breakaway strength of the magnet in ideal conditions – what contributes to it?

The given lifting capacity of the magnet corresponds to the maximum lifting force, measured in a perfect environment, that is:

• with mild steel, used 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
• in normal thermal conditions

What influences lifting capacity in practice

In practice, the holding capacity of a magnet is conditioned by the following aspects, in descending order of 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 was determined with the use of a steel plate with a smooth surface of suitable thickness (min. 20 mm), under vertically applied force, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the lifting capacity.