SMZR 32x225 / N52 - magnetic separator with handle

Strengths and weaknesses of rare earth magnets.

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

• They do not lose power, even during approximately 10 years – the decrease in power is only ~1% (theoretically),
• They are extremely resistant to demagnetization induced by external field influence,
• A magnet with a metallic silver surface is more attractive,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Neodymium magnets are characterized by very 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...
• In view of the potential of precise molding and adaptation to custom projects, neodymium magnets can be created in a wide range of geometric configurations, which expands the range of possible applications,
• Versatile presence in electronics industry – they are used in HDD drives, electric motors, medical equipment, also technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Drawbacks and weaknesses of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon intense impact they can break. 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 power. 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
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited possibility of producing threads in the magnet and complex shapes - preferred is casing - mounting mechanism.
• Health risk related to microscopic parts of magnets can be dangerous, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that tiny parts of these devices can complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Best holding force of the magnet in ideal parameters – what it depends on?

Information about lifting capacity is the result of a measurement for the most favorable conditions, assuming:

• using a sheet made of low-carbon steel, functioning as a circuit closing element
• possessing a massiveness of at least 10 mm to avoid saturation
• with a plane perfectly flat
• under conditions of no distance (metal-to-metal)
• during detachment in a direction perpendicular to the plane
• at room temperature

Determinants of practical lifting force of a magnet

Real force impacted by working environment parameters, including (from most important):

• Distance (between the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under sliding down, the capacity drops significantly, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Plate material – low-carbon steel gives the best results. Alloy admixtures reduce magnetic permeability and lifting capacity.
• Surface structure – the more even the surface, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Temperature influence – high temperature weakens magnetic field. Too high temperature can permanently damage the magnet.

* Lifting capacity was measured using a polished steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.