SM 32x425 [2xM8] / N42 - magnetic separator

Pros as well as cons of NdFeB magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• They retain attractive force for nearly 10 years – the loss is just ~1% (in theory),
• They show high resistance to demagnetization induced by external field influence,
• By covering with a smooth layer of silver, the element acquires an aesthetic look,
• They show high magnetic induction at the operating surface, which affects their effectiveness,
• Thanks to resistance to high temperature, they can operate (depending on the shape) even at temperatures up to 230°C and higher...
• Due to the ability of free molding and customization to individualized requirements, NdFeB magnets can be manufactured in a variety of forms and dimensions, which amplifies use scope,
• Huge importance in modern technologies – they are commonly used in computer drives, electric motors, medical equipment, also industrial machines.
• Thanks to concentrated force, small magnets offer high operating force, occupying minimum space,

Disadvantages of neodymium magnets:

• They are fragile upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets decrease their strength under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• We suggest casing - magnetic holder, due to difficulties in creating nuts inside the magnet and complex forms.
• Possible danger related to microscopic parts of magnets are risky, in case of ingestion, which gains importance in the context of child safety. It is also worth noting that small components of these products can complicate diagnosis medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Detachment force of the magnet in optimal conditions – what affects it?

Holding force of 0 kg is a theoretical maximum value executed under standard conditions:

• with the contact of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• with a thickness of at least 10 mm
• with a plane free of scratches
• under conditions of gap-free contact (metal-to-metal)
• under axial application of breakaway force (90-degree angle)
• at temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

Holding efficiency impacted by working environment parameters, including (from most important):

• Distance (betwixt the magnet and the plate), because even a very small distance (e.g. 0.5 mm) leads to a reduction in force by up to 50% (this also applies to paint, rust or dirt).
• Angle of force application – highest force is reached only during pulling at a 90° angle. The force required to slide of the magnet along the surface is standardly many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Material type – the best choice is pure iron steel. Cast iron may attract less.
• Plate texture – smooth surfaces ensure maximum contact, which improves field saturation. Uneven metal weaken the grip.
• Temperature influence – high temperature reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, in contrast under parallel forces the load capacity is reduced by as much as 75%. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.