SMZR 32x200 / N52 - magnetic separator with handle

Strengths and weaknesses of rare earth magnets.

Besides their exceptional pulling force, neodymium magnets offer the following advantages:

• They retain full power for around ten years – the loss is just ~1% (in theory),
• They show high resistance to demagnetization induced by external magnetic fields,
• By covering with a decorative layer of silver, the element acquires an professional look,
• They are known for high magnetic induction at the operating surface, which affects their effectiveness,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Thanks to flexibility in designing and the capacity to customize to unusual requirements,
• Huge importance in innovative solutions – they are used in magnetic memories, motor assemblies, advanced medical instruments, also complex engineering applications.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Problematic aspects of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a strong case, which not only protects them against impacts but also raises their durability
• Neodymium magnets decrease 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 stability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Limited possibility of making nuts in the magnet and complicated forms - recommended is a housing - magnetic holder.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which becomes key in the context of child safety. It is also worth noting that small elements of these magnets are able to be problematic in diagnostics medical after entering the body.
• With budget limitations the cost of neodymium magnets is a challenge,

Best holding force of the magnet in ideal parameters – what it depends on?

Holding force of 0 kg is a measurement result performed under standard conditions:

• using a sheet made of low-carbon steel, serving as a circuit closing element
• possessing a massiveness of minimum 10 mm to avoid saturation
• with an ideally smooth contact surface
• under conditions of gap-free contact (metal-to-metal)
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Key elements affecting lifting force

During everyday use, the actual holding force results from a number of factors, presented from crucial:

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Angle of force application – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Plate material – mild steel attracts best. Alloy steels decrease magnetic properties and holding force.
• Plate texture – ground elements ensure maximum contact, which improves force. Rough surfaces reduce efficiency.
• Thermal conditions – neodymium magnets have a sensitivity to temperature. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, however under parallel forces the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the load capacity.