SM 18x275 [2xM5] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their consistent power, neodymium magnets have these key benefits:

• Their power is maintained, and after approximately ten years, it drops only by ~1% (according to research),
• They protect against demagnetization induced by ambient electromagnetic environments very well,
• The use of a mirror-like nickel surface provides a refined finish,
• The outer field strength of the magnet shows remarkable magnetic properties,
• With the right combination of compounds, they reach significant thermal stability, enabling operation at or above 230°C (depending on the design),
• The ability for custom shaping or customization to specific needs – neodymium magnets can be manufactured in multiple variants of geometries, which enhances their versatility in applications,
• Wide application in modern technologies – they find application in data storage devices, electromechanical systems, medical equipment and other advanced devices,
• Relatively small size with high magnetic force – neodymium magnets offer strong power in compact dimensions, which makes them ideal in compact constructions

Disadvantages of magnetic elements:

• They may fracture when subjected to a strong impact. If the magnets are exposed to shocks, we recommend in a protective case. The steel housing, in the form of a holder, protects the magnet from damage and additionally increases its overall resistance,
• Magnets lose field strength when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible field weakening (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,
• Magnets exposed to moisture can degrade. Therefore, for outdoor applications, it's best to use waterproof types made of plastic,
• Limited ability to create precision features in the magnet – the use of a magnetic holder is recommended,
• Safety concern linked to microscopic shards may arise, especially if swallowed, which is crucial in the context of child safety. It should also be noted that miniature parts from these devices may interfere with diagnostics after being swallowed,
• In cases of mass production, neodymium magnet cost may not be economically viable,

Breakaway strength of the magnet in ideal conditions – what it depends on?

The given strength of the magnet means the optimal strength, assessed under optimal conditions, namely:

• using a steel plate with low carbon content, serving as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a refined outer layer
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Magnet lifting force in use – key factors

Practical lifting force is determined by factors, 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) 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 performed on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate reduces the load capacity.