SMZR 32x175 / N52 - magnetic separator with handle

Pros as well as cons of rare earth magnets.

Besides their exceptional strength, neodymium magnets offer the following advantages:

• They do not lose magnetism, even over nearly ten years – the reduction in strength is only ~1% (theoretically),
• They possess excellent resistance to weakening of magnetic properties due to opposing magnetic fields,
• In other words, due to the shiny finish of nickel, the element looks attractive,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of custom machining and adjusting to atypical applications,
• Wide application in modern technologies – they serve a role in data components, motor assemblies, precision medical tools, and other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in small systems

Drawbacks and weaknesses of neodymium magnets: weaknesses and usage proposals

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We suggest cover - magnetic mount, due to difficulties in creating threads inside the magnet and complicated shapes.
• Health risk to health – tiny shards of magnets are risky, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, small elements of these magnets are able to be problematic in diagnostics medical after entering the body.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum magnetic pulling force – what affects it?

Magnet power was determined for ideal contact conditions, taking into account:

• on a base made of mild steel, effectively closing the magnetic field
• possessing a massiveness of minimum 10 mm to avoid saturation
• with an polished contact surface
• with direct contact (no paint)
• for force applied at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

In practice, the real power depends on many variables, presented from most significant:

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of generating force.
• Material composition – not every steel reacts the same. High carbon content weaken the attraction effect.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Thermal factor – hot environment weakens pulling force. Too high temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a small distance {between} the magnet’s surface and the plate reduces the holding force.