SM 25x100 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

In addition to their tremendous pulling force, neodymium magnets offer the following advantages:

• They do not lose their power approximately 10 years – the reduction of strength is only ~1% (according to tests),
• They remain magnetized despite exposure to magnetic surroundings,
• By applying a shiny layer of gold, the element gains a modern look,
• The outer field strength of the magnet shows elevated magnetic properties,
• These magnets tolerate elevated temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• The ability for accurate shaping as well as adaptation to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Important function in modern technologies – they find application in data storage devices, electromechanical systems, clinical machines and technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of magnetic elements:

• They are prone to breaking when subjected to a sudden impact. If the magnets are exposed to shocks, it is advisable to use in a steel housing. The steel housing, in the form of a holder, protects the magnet from cracks while also increases its overall strength,
• They lose field intensity at increased temperatures. Most neodymium magnets experience permanent reduction in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• They rust in a humid environment – during outdoor use, we recommend using sealed 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 due to small fragments may arise, in case of ingestion, which is notable in the family environments. Additionally, small elements from these products have the potential to interfere with diagnostics after being swallowed,
• In cases of tight budgets, neodymium magnet cost may be a barrier,

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

The given pulling force of the magnet means the maximum force, assessed in a perfect environment, specifically:

• with mild steel, serving as a magnetic flux conductor
• of a thickness of at least 10 mm
• with a refined outer layer
• in conditions of no clearance
• under perpendicular detachment force
• in normal thermal conditions

Practical lifting capacity: influencing 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, 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 steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.