SM 32x150 [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:

• Their strength is durable, and after approximately 10 years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is among the best,
• The use of a decorative silver surface provides a smooth finish,
• They possess significant magnetic force measurable at the magnet’s surface,
• With the right combination of magnetic alloys, they reach excellent thermal stability, enabling operation at or above 230°C (depending on the design),
• The ability for precise shaping as well as customization to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Key role in cutting-edge sectors – they find application in data storage devices, electromechanical systems, healthcare devices and sophisticated instruments,
• Thanks to their power density, small magnets offer high magnetic performance, while occupying minimal space,

Disadvantages of neodymium magnets:

• They can break when subjected to a strong impact. If the magnets are exposed to shocks, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from breakage while also strengthens its overall resistance,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• They rust in a wet environment. If exposed to rain, we recommend using sealed magnets, such as those made of polymer,
• Limited ability to create complex details in the magnet – the use of a magnetic holder is recommended,
• Health risk from tiny pieces may arise, especially if swallowed, which is notable in the context of child safety. Moreover, miniature parts from these devices can hinder health screening when ingested,
• Due to the price of neodymium, their cost is considerably higher,

Highest magnetic holding force – what affects it?

The given lifting capacity of the magnet represents the maximum lifting force, measured in the best circumstances, specifically:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with zero air gap
• with vertical force applied
• at room temperature

Key elements affecting lifting force

The lifting capacity of a magnet depends on in practice the following factors, ordered from most important to least significant:

• Air gap between the magnet and the plate, because 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 measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a minimal clearance {between} the magnet and the plate decreases the load capacity.