SM 25x125 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

Besides their immense magnetic power, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• They have excellent resistance to magnetic field loss as a result of opposing magnetic fields,
• In other words, due to the glossy layer of nickel, the element looks attractive,
• They feature high magnetic induction at the operating surface, which improves attraction properties,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• In view of the potential of accurate molding and customization to specialized requirements, NdFeB magnets can be manufactured in a wide range of forms and dimensions, which makes them more universal,
• Key role in innovative solutions – they find application in hard drives, drive modules, precision medical tools, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in small systems

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• At strong impacts they can break, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited ability of making threads in the magnet and complex shapes - preferred is cover - mounting mechanism.
• Potential hazard to health – tiny shards of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. Additionally, small components of these magnets are able to complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling force – what contributes to it?

The force parameter is a result of laboratory testing performed under the following configuration:

• with the contact of a yoke made of low-carbon steel, ensuring full magnetic saturation
• with a cross-section no less than 10 mm
• with an ideally smooth contact surface
• without the slightest insulating layer between the magnet and steel
• under axial force direction (90-degree angle)
• in stable room temperature

Determinants of lifting force in real conditions

Please note that the working load may be lower subject to elements below, in order of importance:

• Gap between surfaces – every millimeter of separation (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Direction of force – maximum parameter is available only during pulling at a 90° angle. The shear force of the magnet along the surface is typically many times smaller (approx. 1/5 of the lifting capacity).
• Steel thickness – too thin plate does not accept the full field, causing part of the flux to be lost to the other side.
• Steel grade – ideal substrate is high-permeability steel. Cast iron may have worse magnetic properties.
• Smoothness – ideal contact is obtained only on polished steel. Rough texture create air cushions, reducing force.
• Temperature – heating the magnet causes a temporary drop of force. Check the maximum operating temperature for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, however under shearing force the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate reduces the lifting capacity.