SM 18x175 [2xM5] / N42 - magnetic separator

Pros as well as cons of NdFeB magnets.

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

• Their strength remains stable, and after around 10 years it decreases only by ~1% (according to research),
• They show high resistance to demagnetization induced by external magnetic fields,
• Thanks to the shiny finish, the layer of nickel, gold, or silver gives an elegant appearance,
• Magnets exhibit impressive magnetic induction on the working surface,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to flexibility in constructing and the capacity to adapt to specific needs,
• Key role in modern industrial fields – they serve a role in hard drives, electromotive mechanisms, precision medical tools, also other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously increases its durability.
• NdFeB magnets lose strength 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
• When exposed to humidity, magnets start to rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation as well as corrosion.
• Limited possibility of producing threads in the magnet and complex forms - preferred is cover - magnetic holder.
• Health risk resulting from small fragments of magnets pose a threat, when accidentally swallowed, which is particularly important in the context of child safety. Furthermore, tiny parts of these products can be problematic in diagnostics medical when they are in the body.
• With mass production the cost of neodymium magnets is economically unviable,

Maximum magnetic pulling force – what contributes to it?

Magnet power is the result of a measurement for the most favorable conditions, taking into account:

• with the application of a sheet made of low-carbon steel, ensuring full magnetic saturation
• possessing a thickness of at least 10 mm to avoid saturation
• characterized by lack of roughness
• under conditions of gap-free contact (surface-to-surface)
• during detachment in a direction vertical to the mounting surface
• in temp. approx. 20°C

Determinants of lifting force in real conditions

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

• Space between surfaces – every millimeter of separation (caused e.g. by varnish or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to pulling vertically. When applying parallel force, the magnet holds much less (often approx. 20-30% of nominal force).
• Metal thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Steel type – low-carbon steel attracts best. Alloy admixtures lower magnetic properties and holding force.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases force. Rough surfaces weaken the grip.
• Operating temperature – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures they can be stronger (up to a certain limit).

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