SM 32x500 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of rare earth magnets.

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

• They have stable power, and over nearly ten years their performance decreases symbolically – ~1% (in testing),
• They feature excellent resistance to magnetic field loss due to external fields,
• Thanks to the glossy finish, the coating of Ni-Cu-Ni, gold, or silver-plated gives an visually attractive appearance,
• Neodymium magnets ensure maximum magnetic induction on a small area, which increases force concentration,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Possibility of detailed machining and adapting to specific applications,
• Versatile presence in innovative solutions – they are utilized in HDD drives, electric motors, medical devices, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which allows their use in compact constructions

Cons of neodymium magnets and ways of using them

• To avoid cracks under impact, we recommend using special steel housings. Such a solution secures the magnet and simultaneously improves its durability.
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Limited possibility of creating nuts in the magnet and complex shapes - preferred is a housing - magnet mounting.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which gains importance in the aspect of protecting the youngest. It is also worth noting that small components of these devices are able to disrupt the diagnostic process medical in case of swallowing.
• With mass production the cost of neodymium magnets is a challenge,

Optimal lifting capacity of a neodymium magnet – what contributes to it?

Breakaway force was defined for ideal contact conditions, assuming:

• on a block made of mild steel, optimally conducting the magnetic flux
• possessing a massiveness of min. 10 mm to avoid saturation
• characterized by smoothness
• under conditions of ideal adhesion (metal-to-metal)
• for force acting at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

Please note that the application force will differ influenced by elements below, starting with the most relevant:

• Gap between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) significantly weakens the magnet efficiency, often by half at just 0.5 mm.
• Loading method – catalog parameter refers to detachment vertically. When applying parallel force, the magnet exhibits much less (often approx. 20-30% of maximum force).
• Element thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice 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, reducing force.
• Temperature influence – high temperature weakens pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity was determined with the use of a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, whereas under parallel forces the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the holding force.