SM 32x100 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of neodymium magnets.

Besides their immense magnetic power, neodymium magnets offer the following advantages:

• They retain attractive force for around ten years – the loss is just ~1% (based on simulations),
• They possess excellent resistance to magnetism drop as a result of external magnetic sources,
• In other words, due to the shiny surface of silver, the element gains visual value,
• Magnets are distinguished by extremely high magnetic induction on the working surface,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Thanks to versatility in constructing and the capacity to modify to complex applications,
• Wide application in electronics industry – they serve a role in data components, electric drive systems, diagnostic systems, also industrial machines.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Problematic aspects of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets decrease their strength 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 durability 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 those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest cover - magnetic mount, due to difficulties in producing threads inside the magnet and complex shapes.
• Possible danger to health – tiny shards of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. Furthermore, small elements of these magnets can complicate diagnosis medical when they are in the body.
• With budget limitations the cost of neodymium magnets is economically unviable,

Maximum holding power of the magnet – what affects it?

The specified lifting capacity refers to the limit force, obtained under ideal test conditions, meaning:

• using a sheet made of mild steel, functioning as a circuit closing element
• with a thickness no less than 10 mm
• characterized by even structure
• under conditions of gap-free contact (metal-to-metal)
• under perpendicular application of breakaway force (90-degree angle)
• at standard ambient temperature

Determinants of practical lifting force of a magnet

Please note that the magnet holding will differ influenced by elements below, in order of importance:

• Clearance – existence of any layer (rust, dirt, air) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is reached only during perpendicular pulling. The shear force of the magnet along the surface is usually many times lower (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel grade – ideal substrate is high-permeability steel. Stainless steels may have worse magnetic properties.
• Plate texture – smooth surfaces ensure maximum contact, which increases field saturation. Rough surfaces weaken the grip.
• Thermal factor – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was measured with the use of a polished steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under attempts to slide the magnet the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate decreases the holding force.