SM 25x250 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of rare earth magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• They have stable power, and over nearly 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Magnets effectively resist against demagnetization caused by foreign field sources,
• In other words, due to the shiny surface of silver, the element is aesthetically pleasing,
• They feature high magnetic induction at the operating surface, which affects their effectiveness,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to the possibility of flexible molding and customization to individualized solutions, neodymium magnets can be produced in a variety of shapes and sizes, which makes them more universal,
• Versatile presence in electronics industry – they find application in HDD drives, motor assemblies, precision medical tools, also multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which enables their usage in miniature devices

Disadvantages of NdFeB magnets:

• They are prone to damage upon too strong impacts. To avoid cracks, it is worth protecting magnets in a protective case. Such protection not only shields the magnet but also increases its resistance to damage
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their power 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
• They oxidize in a humid environment. For use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing nuts and complex forms in magnets, we propose using casing - magnetic mechanism.
• Potential hazard to health – tiny shards of magnets are risky, when accidentally swallowed, which becomes key in the context of child health protection. Furthermore, small elements of these products are able to complicate diagnosis medical after entering the body.
• Due to complex production process, their price exceeds standard values,

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

The declared magnet strength represents the maximum value, measured under ideal test conditions, specifically:

• using a plate made of low-carbon steel, functioning as a ideal flux conductor
• possessing a thickness of minimum 10 mm to ensure full flux closure
• characterized by smoothness
• with direct contact (without coatings)
• for force acting at a right angle (in the magnet axis)
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

In practice, the actual holding force is determined by a number of factors, presented from most significant:

• Clearance – existence of foreign body (paint, tape, air) acts as an insulator, which reduces power rapidly (even by 50% at 0.5 mm).
• Load vector – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material type – ideal substrate is high-permeability steel. Hardened steels may have worse magnetic properties.
• Surface quality – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Temperature – temperature increase results in weakening of force. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity was determined using a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.