SMZR 32x225 / N52 - magnetic separator with handle

Advantages and disadvantages of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain attractive force for around ten years – the drop is just ~1% (according to analyses),
• They do not lose their magnetic properties even under external field action,
• In other words, due to the aesthetic finish of nickel, the element is aesthetically pleasing,
• Magnets possess huge magnetic induction on the outer layer,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Considering the ability of precise shaping and adaptation to unique solutions, magnetic components can be created in a wide range of shapes and sizes, which increases their versatility,
• Key role in modern industrial fields – they are used in hard drives, electromotive mechanisms, diagnostic systems, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which enables their usage in miniature devices

What to avoid - cons of neodymium magnets: application proposals

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also improves its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in force. 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 oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic holder, due to difficulties in creating threads inside the magnet and complex shapes.
• Health risk resulting from small fragments of magnets are risky, when accidentally swallowed, which is particularly important in the context of child health protection. Additionally, tiny parts of these devices can disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Magnetic strength at its maximum – what it depends on?

The lifting capacity listed is a theoretical maximum value executed under standard conditions:

• with the contact of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• possessing a thickness of min. 10 mm to ensure full flux closure
• with a plane perfectly flat
• with zero gap (without paint)
• under vertical application of breakaway force (90-degree angle)
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

It is worth knowing that the working load may be lower depending on the following factors, in order of importance:

• Distance – existence of any layer (rust, dirt, gap) acts as an insulator, which lowers capacity steeply (even by 50% at 0.5 mm).
• Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the surface is typically several times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin sheet does not accept the full field, causing part of the flux to be lost into the air.
• Material type – the best choice is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface quality – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Temperature – heating the magnet causes a temporary drop of induction. Check the thermal limit for a given model.

* Lifting capacity was determined using a smooth steel plate of optimal thickness (min. 20 mm), under perpendicular pulling force, however under parallel forces the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.