SMZR 32x225 / N52 - magnetic separator with handle

Advantages and disadvantages of rare earth magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (according to literature),
• They maintain their magnetic properties even under close interference source,
• Thanks to the glossy finish, the plating of nickel, gold, or silver gives an elegant appearance,
• Neodymium magnets generate maximum magnetic induction on a small surface, which increases force concentration,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• Possibility of exact shaping and optimizing to precise conditions,
• Huge importance in high-tech industry – they are utilized in data components, brushless drives, precision medical tools, as well as modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth protecting magnets using a steel holder. Such protection not only protects the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding 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 and corrosion.
• Limited possibility of making nuts in the magnet and complex forms - preferred is casing - mounting mechanism.
• Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the context of child safety. Additionally, small elements of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• With budget limitations the cost of neodymium magnets can be a barrier,

Maximum lifting force for a neodymium magnet – what it depends on?

The lifting capacity listed is a result of laboratory testing performed under standard conditions:

• on a block made of structural steel, perfectly concentrating the magnetic field
• with a cross-section of at least 10 mm
• with a plane perfectly flat
• with direct contact (no paint)
• for force acting at a right angle (pull-off, not shear)
• at room temperature

What influences lifting capacity in practice

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

• Clearance – existence of any layer (rust, dirt, air) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is available only during perpendicular pulling. The force required to slide of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Steel thickness – too thin steel causes magnetic saturation, causing part of the power to be lost into the air.
• Chemical composition of the base – low-carbon steel attracts best. Alloy steels lower magnetic permeability and lifting capacity.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Temperature influence – high temperature weakens magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Holding force was tested 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 small distance {between} the magnet and the plate decreases the load capacity.