SM 32x275 [2xM8] / N52 - magnetic separator

Pros as well as cons of rare earth magnets.

Besides their exceptional field intensity, neodymium magnets offer the following advantages:

• They virtually do not lose power, because even after 10 years the performance loss is only ~1% (in laboratory conditions),
• They feature excellent resistance to magnetism drop due to external fields,
• A magnet with a shiny gold surface is more attractive,
• Neodymium magnets ensure maximum magnetic induction on a small area, which allows for strong attraction,
• 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 modeling as well as modifying to specific applications,
• Huge importance in innovative solutions – they are used in hard drives, electric motors, advanced medical instruments, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which makes them useful in small systems

Cons of neodymium magnets and proposals for their use:

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can fracture. We recommend keeping them in a steel housing, which not only protects them against impacts but also raises their 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
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Due to limitations in producing threads and complicated forms in magnets, we recommend using casing - magnetic mount.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the context of child safety. Furthermore, small elements of these products are able to disrupt the diagnostic process medical when they are in the body.
• Due to expensive raw materials, their price is relatively high,

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

The specified lifting capacity represents the peak performance, obtained under ideal test conditions, meaning:

• using a plate made of high-permeability steel, serving as a magnetic yoke
• whose transverse dimension is min. 10 mm
• with a surface perfectly flat
• under conditions of no distance (metal-to-metal)
• under vertical application of breakaway force (90-degree angle)
• at standard ambient temperature

Determinants of lifting force in real conditions

Real force is affected by specific conditions, mainly (from priority):

• Clearance – existence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Angle of force application – highest force is reached only during perpendicular pulling. The force required to slide of the magnet along the plate is usually several times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of converting into lifting capacity.
• Steel grade – the best choice is pure iron steel. Stainless steels may have worse magnetic properties.
• Plate texture – smooth surfaces ensure maximum contact, which increases field saturation. Rough surfaces reduce efficiency.
• Thermal factor – high temperature weakens pulling force. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was measured using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, however under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate lowers the load capacity.