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

Pros and cons of rare earth magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They retain magnetic properties for around ten years – the loss is just ~1% (based on simulations),
• They do not lose their magnetic properties even under external field action,
• Thanks to the reflective finish, the surface of Ni-Cu-Ni, gold-plated, or silver gives an elegant appearance,
• Magnetic induction on the working part of the magnet is extremely intense,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Due to the possibility of free molding and customization to specialized solutions, NdFeB magnets can be manufactured in a broad palette of shapes and sizes, which expands the range of possible applications,
• Versatile presence in future technologies – they are used in data components, drive modules, diagnostic systems, also multitasking production systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium 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 very resistant to heat
• When exposed to humidity, magnets start to rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation as well as corrosion.
• We suggest a housing - magnetic holder, due to difficulties in creating nuts inside the magnet and complex forms.
• Health risk to health – tiny shards of magnets can be dangerous, in case of ingestion, which gains importance in the aspect of protecting the youngest. It is also worth noting that small elements of these devices are able to be problematic in diagnostics medical when they are in the body.
• Due to expensive raw materials, their price is higher than average,

Breakaway strength of the magnet in ideal conditions – what it depends on?

The declared magnet strength concerns the limit force, measured under laboratory conditions, meaning:

• with the contact of a sheet made of special test steel, guaranteeing maximum field concentration
• whose transverse dimension reaches at least 10 mm
• with a plane perfectly flat
• without any clearance between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at conditions approx. 20°C

Key elements affecting lifting force

It is worth knowing that the magnet holding may be lower depending on the following factors, starting with the most relevant:

• Space between surfaces – even a fraction of a millimeter of separation (caused e.g. by varnish or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to detachment vertically. When slipping, the magnet holds much less (typically approx. 20-30% of maximum force).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal restricts the lifting capacity (the magnet "punches through" it).
• Plate material – low-carbon steel attracts best. Alloy steels lower magnetic permeability and holding force.
• Plate texture – smooth surfaces ensure maximum contact, which improves force. Rough surfaces weaken the grip.
• Heat – neodymium magnets have a negative temperature coefficient. When it is hot they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under perpendicular forces, however under attempts to slide the magnet the lifting capacity is smaller. In addition, even a small distance {between} the magnet and the plate reduces the holding force.