SM 25x150 [2xM8] / N42 - magnetic separator

Strengths and weaknesses of rare earth magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• They retain full power for nearly 10 years – the loss is just ~1% (according to analyses),
• Magnets very well defend themselves against loss of magnetization caused by external fields,
• A magnet with a smooth silver surface has an effective appearance,
• Neodymium magnets achieve maximum magnetic induction on a their surface, which ensures high operational effectiveness,
• 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 detailed shaping as well as adjusting to atypical requirements,
• Huge importance in electronics industry – they serve a role in HDD drives, brushless drives, medical equipment, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Cons of neodymium magnets and ways of using them

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also improves its resistance to damage
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape as well as 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 rust in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• We recommend a housing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complicated shapes.
• Possible danger to health – tiny shards of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets are able to complicate diagnosis medical after entering the body.
• Due to expensive raw materials, their price exceeds standard values,

Breakaway strength of the magnet in ideal conditions – what it depends on?

Breakaway force was determined for optimal configuration, including:

• with the contact of a yoke made of special test steel, ensuring maximum field concentration
• whose transverse dimension is min. 10 mm
• characterized by even structure
• without the slightest clearance between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

During everyday use, the actual holding force depends on several key aspects, presented from most significant:

• Distance – the presence of any layer (paint, tape, air) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. High carbon content weaken the attraction effect.
• Base smoothness – the more even the surface, the larger the contact zone and stronger the hold. Roughness acts like micro-gaps.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity was assessed using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the load capacity is reduced by as much as fivefold. Additionally, even a minimal clearance {between} the magnet and the plate lowers the load capacity.