SMZR 25x100 / N52 - magnetic separator with handle

Pros and cons of neodymium magnets.

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

• They do not lose magnetism, even over nearly 10 years – the reduction in lifting capacity is only ~1% (based on measurements),
• They maintain their magnetic properties even under strong external field,
• By applying a reflective coating of gold, the element acquires an aesthetic look,
• They are known for high magnetic induction at the operating surface, making them more effective,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Possibility of individual creating as well as optimizing to atypical needs,
• Universal use in modern industrial fields – they are commonly used in HDD drives, electric motors, precision medical tools, also other advanced devices.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we advise placing them in special holders. 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 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. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation as well as corrosion.
• Due to limitations in realizing nuts and complex forms in magnets, we recommend using cover - magnetic mechanism.
• Possible danger to health – tiny shards of magnets can be dangerous, in case of ingestion, which gains importance in the aspect of protecting the youngest. Additionally, small elements of these products can disrupt the diagnostic process medical in case of swallowing.
• Due to complex production process, their price exceeds standard values,

Maximum holding power of the magnet – what contributes to it?

Breakaway force is the result of a measurement for optimal configuration, including:

• with the contact of a sheet made of low-carbon steel, ensuring full magnetic saturation
• with a cross-section minimum 10 mm
• characterized by lack of roughness
• without the slightest clearance between the magnet and steel
• during pulling in a direction vertical to the mounting surface
• in temp. approx. 20°C

Determinants of lifting force in real conditions

It is worth knowing that the working load will differ subject to the following factors, starting with the most relevant:

• Distance – existence of foreign body (rust, dirt, gap) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick sheet does not accept the full field, causing part of the power to be escaped to the other side.
• Steel type – low-carbon steel attracts best. Alloy steels reduce magnetic permeability and holding force.
• Base smoothness – the smoother and more polished the surface, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal factor – hot environment weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate decreases the lifting capacity.