SM 25x175 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

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

• They retain magnetic properties for nearly 10 years – the drop is just ~1% (according to analyses),
• They retain their magnetic properties even under close interference source,
• In other words, due to the smooth layer of nickel, the element gains a professional look,
• Neodymium magnets generate maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• Possibility of detailed machining as well as modifying to precise applications,
• Significant place in electronics industry – they are used in hard drives, drive modules, diagnostic systems, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which allows their use in small systems

Disadvantages of neodymium magnets:

• At strong impacts they can break, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage and increases the magnet's durability.
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can corrode. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• We suggest cover - magnetic holder, due to difficulties in creating threads inside the magnet and complex shapes.
• Possible danger resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which gains importance in the context of child health protection. Furthermore, small components of these devices are able to complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what affects it?

The force parameter is a result of laboratory testing executed under specific, ideal conditions:

• on a block made of mild steel, perfectly concentrating the magnetic field
• possessing a massiveness of min. 10 mm to ensure full flux closure
• characterized by lack of roughness
• with zero gap (without coatings)
• for force acting at a right angle (pull-off, not shear)
• at temperature room level

Practical aspects of lifting capacity – factors

In real-world applications, the real power results from a number of factors, presented from most significant:

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Force direction – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops significantly, often to levels of 20-30% of the nominal value.
• Plate thickness – too thin plate causes magnetic saturation, causing part of the flux to be wasted into the air.
• Material composition – different alloys attracts identically. High carbon content worsen the attraction effect.
• Base smoothness – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Thermal factor – hot environment reduces magnetic field. Too high temperature can permanently demagnetize the magnet.

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.