SM 25x200 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

Apart from their consistent holding force, neodymium magnets have these key benefits:

• They retain magnetic properties for almost ten years – the loss is just ~1% (in theory),
• Neodymium magnets prove to be highly resistant to loss of magnetic properties caused by external interference,
• In other words, due to the metallic surface of nickel, the element becomes visually attractive,
• Magnetic induction on the working part of the magnet turns out to be extremely intense,
• 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 customization to specialized requirements, magnetic components can be modeled in a broad palette of shapes and sizes, which increases their versatility,
• Versatile presence in innovative solutions – they are commonly used in magnetic memories, drive modules, precision medical tools, also multitasking production systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

What to avoid - cons of neodymium magnets: weaknesses and usage proposals

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent drop of power (a factor is the shape and 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
• 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 ability of making nuts in the magnet and complex forms - preferred is cover - magnetic holder.
• Potential hazard related to microscopic parts of magnets can be dangerous, if swallowed, which is particularly important in the context of child health protection. Furthermore, small elements of these magnets are able to complicate diagnosis medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Detachment force of the magnet in optimal conditions – what contributes to it?

Holding force of 0 kg is a theoretical maximum value conducted under standard conditions:

• with the contact of a sheet made of special test steel, guaranteeing maximum field concentration
• whose thickness is min. 10 mm
• characterized by smoothness
• under conditions of gap-free contact (surface-to-surface)
• during detachment in a direction perpendicular to the plane
• at standard ambient temperature

Lifting capacity in practice – influencing factors

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

• Distance – existence of any layer (rust, dirt, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity testing was conducted on plates with a smooth surface of suitable thickness, under a perpendicular pulling force, whereas under parallel forces the load capacity is reduced by as much as 75%. In addition, even a minimal clearance {between} the magnet and the plate lowers the load capacity.