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

Pros as well as cons of NdFeB magnets.

In addition to their magnetic capacity, neodymium magnets provide the following advantages:

• Their magnetic field is durable, and after approximately 10 years it drops only by ~1% (theoretically),
• Magnets effectively defend themselves against loss of magnetization caused by external fields,
• By covering with a decorative coating of silver, the element acquires an proper look,
• Neodymium magnets create maximum magnetic induction on a their surface, which increases force concentration,
• 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...
• Thanks to the ability of flexible shaping and adaptation to unique needs, neodymium magnets can be manufactured in a broad palette of forms and dimensions, which amplifies use scope,
• Huge importance in innovative solutions – they serve a role in hard drives, electric drive systems, diagnostic systems, also industrial machines.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• 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 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
• When exposed to humidity, magnets usually 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.
• Due to limitations in realizing threads and complex shapes in magnets, we propose using casing - magnetic holder.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these products can complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Optimal lifting capacity of a neodymium magnet – what it depends on?

Magnet power is the result of a measurement for optimal configuration, including:

• with the contact of a yoke made of special test steel, ensuring maximum field concentration
• whose thickness equals approx. 10 mm
• with an ideally smooth touching surface
• with direct contact (without paint)
• during detachment in a direction perpendicular to the mounting surface
• at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

It is worth knowing that the working load will differ depending on the following factors, starting with the most relevant:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet has greatest strength perpendicularly. Under shear forces, the capacity drops significantly, often to levels of 20-30% of the maximum value.
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet restricts the attraction force (the magnet "punches through" it).
• Material type – ideal substrate is pure iron steel. Cast iron may generate lower lifting capacity.
• Surface finish – ideal contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment reduces pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was determined using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate decreases the load capacity.