SM 32x325 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They virtually do not lose power, because even after 10 years, the performance loss is only ~1% (based on calculations),
• Their ability to resist magnetic interference from external fields is impressive,
• The use of a mirror-like gold surface provides a eye-catching finish,
• They possess significant magnetic force measurable at the magnet’s surface,
• These magnets tolerate extreme temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• Thanks to the freedom in shaping and the capability to adapt to unique requirements, neodymium magnets can be created in different geometries, which expands their application range,
• Wide application in advanced technical fields – they find application in computer drives, electromechanical systems, medical equipment and technologically developed systems,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in small dimensions, which makes them ideal in compact constructions

Disadvantages of neodymium magnets:

• They may fracture when subjected to a heavy impact. If the magnets are exposed to external force, they should be placed in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage while also strengthens its overall resistance,
• They lose strength 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,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, it's best to use waterproof types made of rubber,
• The use of a protective casing or external holder is recommended, since machining threads in neodymium magnets is risky,
• Possible threat linked to microscopic shards may arise, when consumed by mistake, which is crucial in the health of young users. Moreover, minuscule fragments from these assemblies have the potential to hinder health screening if inside the body,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Optimal lifting capacity of a neodymium magnet – what contributes to it?

The given lifting capacity of the magnet represents the maximum lifting force, determined under optimal conditions, specifically:

• with the use of low-carbon steel plate serving as a magnetic yoke
• of a thickness of at least 10 mm
• with a smooth surface
• with no separation
• under perpendicular detachment force
• in normal thermal conditions

Key elements affecting lifting force

Practical lifting force is dependent on elements, listed from the most critical to the less significant:

• Air gap between the magnet and the plate, since even a very small distance (e.g. 0.5 mm) can cause 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 by applying a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the lifting capacity is smaller. Moreover, even a small distance {between} the magnet and the plate decreases the lifting capacity.