SM 18x175 [2xM5] / N42 - magnetic separator

Pros as well as cons of rare earth magnets.

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

• They have unchanged lifting capacity, and over nearly ten years their attraction force decreases symbolically – ~1% (according to theory),
• They have excellent resistance to weakening of magnetic properties as a result of external fields,
• A magnet with a metallic nickel surface has an effective appearance,
• The surface of neodymium magnets generates a maximum magnetic field – this is a key feature,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to freedom in designing and the capacity to adapt to client solutions,
• Significant place in future technologies – they are utilized in data components, electric motors, precision medical tools, also other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• At strong impacts they can crack, therefore we advise placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They rust in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited possibility of making threads in the magnet and complex forms - recommended is casing - mounting mechanism.
• Potential hazard resulting from small fragments of magnets are risky, in case of ingestion, which gains importance in the context of child safety. Furthermore, tiny parts of these magnets can disrupt the diagnostic process medical in case of swallowing.
• Due to neodymium price, their price exceeds standard values,

Magnetic strength at its maximum – what affects it?

The declared magnet strength concerns the limit force, measured under laboratory conditions, specifically:

• with the contact of a sheet made of special test steel, guaranteeing full magnetic saturation
• with a cross-section no less than 10 mm
• characterized by lack of roughness
• with direct contact (without impurities)
• during detachment in a direction perpendicular to the plane
• at conditions approx. 20°C

Practical aspects of lifting capacity – factors

It is worth knowing that the application force may be lower subject to the following factors, starting with the most relevant:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by varnish or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Metal type – different alloys reacts the same. Alloy additives weaken the interaction with the magnet.
• Surface finish – full contact is obtained only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently damage the magnet.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, in contrast under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the lifting capacity.