SM 25x200 [2xM8] / N52 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They retain magnetic properties for nearly 10 years – the loss is just ~1% (in theory),
• Neodymium magnets are remarkably resistant to loss of magnetic properties caused by external field sources,
• Thanks to the glossy finish, the layer of nickel, gold, or silver-plated gives an modern appearance,
• Neodymium magnets generate maximum magnetic induction on a small surface, which increases force concentration,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the shape) even at high temperatures reaching 230°C or more...
• In view of the option of precise molding and adaptation to specialized requirements, neodymium magnets can be manufactured in a wide range of shapes and sizes, which makes them more universal,
• Fundamental importance in modern industrial fields – they are commonly used in computer drives, electromotive mechanisms, precision medical tools, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in compact constructions

Disadvantages of NdFeB magnets:

• At strong impacts they can crack, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's 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
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• We recommend a housing - magnetic mechanism, due to difficulties in producing nuts inside the magnet and complicated forms.
• Potential hazard related to microscopic parts of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child safety. Additionally, small elements of these magnets are able to complicate diagnosis medical when they are in the body.
• With mass production the cost of neodymium magnets is a challenge,

Highest magnetic holding force – what affects it?

The specified lifting capacity represents the peak performance, recorded under optimal environment, namely:

• using a base made of high-permeability steel, acting as a magnetic yoke
• whose transverse dimension reaches at least 10 mm
• with a surface perfectly flat
• without any insulating layer between the magnet and steel
• under perpendicular force direction (90-degree angle)
• in temp. approx. 20°C

Impact of factors on magnetic holding capacity in practice

Please note that the magnet holding will differ subject to the following factors, starting with the most relevant:

• Distance (between the magnet and the metal), since even a tiny clearance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or dirt).
• Direction of force – maximum parameter is obtained only during pulling at a 90° angle. The force required to slide of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Steel grade – the best choice is high-permeability steel. Cast iron may generate lower lifting capacity.
• Base smoothness – the more even the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.