SM 32x225 [2xM8] / N42 - magnetic separator

Strengths as well as weaknesses of neodymium magnets.

Besides their exceptional strength, neodymium magnets offer the following advantages:

• Their strength remains stable, and after approximately ten years it decreases only by ~1% (theoretically),
• Magnets effectively defend themselves against demagnetization caused by foreign field sources,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to present itself better,
• Neodymium magnets generate maximum magnetic induction on a contact point, which allows for strong attraction,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Possibility of exact machining as well as adapting to individual requirements,
• Fundamental importance in future technologies – they are utilized in mass storage devices, electromotive mechanisms, precision medical tools, as well as complex engineering applications.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets and proposals for their use:

• To avoid cracks under impact, we recommend using special steel housings. Such a solution protects the magnet and simultaneously increases its durability.
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of making nuts in the magnet and complicated forms - recommended is cover - mounting mechanism.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, small components of these magnets can disrupt the diagnostic process medical when they are in the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Optimal lifting capacity of a neodymium magnet – what affects it?

Magnet power was defined for the most favorable conditions, assuming:

• using a plate made of low-carbon steel, serving as a ideal flux conductor
• whose thickness is min. 10 mm
• with a surface cleaned and smooth
• without the slightest clearance between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• at conditions approx. 20°C

What influences lifting capacity in practice

Holding efficiency impacted by specific conditions, including (from most important):

• Space between magnet and steel – every millimeter of separation (caused e.g. by varnish or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds significantly lower power (typically approx. 20-30% of maximum force).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Chemical composition of the base – low-carbon steel attracts best. Alloy admixtures lower magnetic permeability and lifting capacity.
• Surface finish – ideal contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Thermal factor – hot environment weakens magnetic field. Too high temperature can permanently damage the magnet.

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under shearing force the load capacity is reduced by as much as 5 times. Moreover, even a small distance {between} the magnet’s surface and the plate reduces the holding force.