SM 32x375 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of rare earth magnets.

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

• Their magnetic field is maintained, and after around 10 years it decreases only by ~1% (theoretically),
• They are noted for resistance to demagnetization induced by presence of other magnetic fields,
• A magnet with a smooth silver surface has better aesthetics,
• Neodymium magnets achieve maximum magnetic induction on a small surface, which increases force concentration,
• 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...
• Possibility of detailed forming and adjusting to specific needs,
• Significant place in advanced technology sectors – they find application in computer drives, electromotive mechanisms, diagnostic systems, as well as multitasking production systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Characteristics of disadvantages of neodymium magnets: application proposals

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• NdFeB magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complicated forms in magnets, we recommend using casing - magnetic mechanism.
• Health risk related to microscopic parts of magnets pose a threat, if swallowed, which is particularly important in the context of child safety. Additionally, tiny parts of these devices can complicate diagnosis medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which can limit application in large quantities

Maximum magnetic pulling force – what it depends on?

The specified lifting capacity represents the peak performance, obtained under laboratory conditions, specifically:

• with the contact of a yoke made of special test steel, ensuring full magnetic saturation
• possessing a massiveness of at least 10 mm to avoid saturation
• characterized by even structure
• without the slightest air gap between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at room temperature

Magnet lifting force in use – key factors

In practice, the actual holding force depends on a number of factors, presented from crucial:

• Distance (betwixt the magnet and the plate), because even a very small distance (e.g. 0.5 mm) leads to a drastic drop in force by up to 50% (this also applies to varnish, corrosion or debris).
• Angle of force application – highest force is available only during perpendicular pulling. The shear force of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – low-carbon steel attracts best. Alloy admixtures decrease magnetic permeability and lifting capacity.
• Surface condition – ground elements guarantee perfect abutment, which increases force. Uneven metal weaken the grip.
• Thermal environment – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity was measured by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under attempts to slide the magnet the lifting capacity is smaller. In addition, even a slight gap {between} the magnet and the plate lowers the lifting capacity.