SM 18x200 [2xM5] / N42 - magnetic separator

Strengths as well as weaknesses of NdFeB magnets.

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

• They have constant strength, and over around 10 years their performance decreases symbolically – ~1% (according to theory),
• Neodymium magnets prove to be remarkably resistant to demagnetization caused by external interference,
• A magnet with a shiny nickel surface is more attractive,
• They are known for high magnetic induction at the operating surface, which affects their effectiveness,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate forming as well as modifying to atypical conditions,
• Significant place in future technologies – they are commonly used in mass storage devices, drive modules, advanced medical instruments, as well as other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as 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 corrode. Therefore when using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in creating threads and complicated forms in magnets, we propose using cover - magnetic holder.
• Health risk related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that small elements of these products are able to be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which can limit application in large quantities

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

The declared magnet strength concerns the limit force, obtained under ideal test conditions, namely:

• using a base made of low-carbon steel, acting as a ideal flux conductor
• with a cross-section no less than 10 mm
• with a plane perfectly flat
• without any air gap between the magnet and steel
• during detachment in a direction vertical to the plane
• in neutral thermal conditions

Determinants of practical lifting force of a magnet

Holding efficiency is affected by working environment parameters, mainly (from most important):

• Distance – existence of any layer (paint, tape, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds significantly lower power (typically approx. 20-30% of maximum force).
• Plate thickness – insufficiently thick steel causes magnetic saturation, causing part of the flux to be lost into the air.
• Material composition – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Surface structure – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Temperature – heating the magnet causes a temporary drop of force. It is worth remembering the maximum operating temperature for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, however under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.