SM 32x375 [2xM8] / N42 - magnetic separator

Advantages as well as disadvantages of neodymium magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They have constant strength, and over more than 10 years their attraction force decreases symbolically – ~1% (according to theory),
• They feature excellent resistance to magnetism drop when exposed to external fields,
• The use of an metallic coating of noble metals (nickel, gold, silver) causes the element to look better,
• Magnets are characterized by huge magnetic induction on the active area,
• Thanks to resistance to high temperature, they are able to function (depending on the shape) even at temperatures up to 230°C and higher...
• Possibility of accurate shaping and modifying to concrete applications,
• Versatile presence in electronics industry – they are commonly used in mass storage devices, drive modules, diagnostic systems, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in compact constructions

What to avoid - cons of neodymium magnets: application proposals

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a special holder, which not only secures them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets suffer a drop in strength. Often, when the temperature exceeds 80°C, their power decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in realizing nuts and complex forms in magnets, we propose using casing - magnetic holder.
• Health risk to health – tiny shards of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. Furthermore, small elements of these magnets can complicate diagnosis medical after entering the body.
• Due to expensive raw materials, their price exceeds standard values,

Maximum lifting capacity of the magnet – what it depends on?

The declared magnet strength concerns the limit force, recorded under optimal environment, specifically:

• with the application of a sheet made of special test steel, guaranteeing maximum field concentration
• whose thickness is min. 10 mm
• characterized by even structure
• with direct contact (no coatings)
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

What influences lifting capacity in practice

Holding efficiency is influenced by working environment parameters, mainly (from priority):

• Clearance – existence of any layer (rust, dirt, air) acts as an insulator, which lowers power rapidly (even by 50% at 0.5 mm).
• Load vector – maximum parameter is available only during pulling at a 90° angle. The shear force of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – to utilize 100% power, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material type – the best choice is pure iron steel. Cast iron may attract less.
• Surface finish – full contact is possible only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Temperature – heating the magnet results in weakening of force. Check the thermal limit for a given model.

* Lifting capacity was measured by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, whereas under shearing force the holding force is lower. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.