SM 32x375 [2xM8] / N42 - magnetic separator

Pros as well as cons of neodymium magnets.

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

• They do not lose magnetism, even after nearly ten years – the drop in power is only ~1% (based on measurements),
• They are resistant to demagnetization induced by external field influence,
• A magnet with a metallic gold surface looks better,
• Magnetic induction on the working part of the magnet is extremely intense,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for functioning at temperatures approaching 230°C and above...
• Thanks to versatility in designing and the ability to adapt to specific needs,
• Key role in high-tech industry – they find application in computer drives, drive modules, medical equipment, and modern systems.
• Thanks to concentrated force, small magnets offer high operating force, occupying minimum space,

Characteristics of disadvantages of neodymium magnets: application proposals

• Brittleness is one of their disadvantages. Upon strong impact they can break. We recommend keeping them in a steel housing, which not only protects them against impacts but also increases their durability
• NdFeB magnets lose force when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• 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 and corrosion.
• Limited ability of producing nuts in the magnet and complicated forms - recommended is cover - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, if swallowed, which gains importance in the context of child safety. Additionally, tiny parts of these magnets can disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The specified lifting capacity concerns the limit force, recorded under ideal test conditions, meaning:

• on a plate made of structural steel, perfectly concentrating the magnetic field
• with a thickness of at least 10 mm
• with a surface free of scratches
• without the slightest insulating layer between the magnet and steel
• under axial application of breakaway force (90-degree angle)
• at temperature approx. 20 degrees Celsius

Lifting capacity in real conditions – factors

In practice, the real power is determined by many variables, presented from most significant:

• Gap (between the magnet and the plate), since even a tiny clearance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Load vector – highest force is available only during perpendicular pulling. The force required to slide of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – too thin sheet causes magnetic saturation, causing part of the flux to be wasted into the air.
• Material type – ideal substrate is high-permeability steel. Hardened steels may generate lower lifting capacity.
• Surface structure – the smoother and more polished the surface, the larger the contact zone and stronger the hold. Unevenness creates an air distance.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under perpendicular forces, in contrast under shearing force the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet’s surface and the plate lowers the holding force.