SM 25x225 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

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

• They have stable power, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• They are noted for resistance to demagnetization induced by external magnetic fields,
• In other words, due to the aesthetic layer of nickel, the element gains a professional look,
• Magnets exhibit very high magnetic induction on the outer side,
• Through (appropriate) combination of ingredients, they can achieve high thermal resistance, allowing for action at temperatures approaching 230°C and above...
• Possibility of individual shaping and modifying to precise conditions,
• Universal use in modern industrial fields – they are utilized in data components, electromotive mechanisms, advanced medical instruments, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which enables their usage in miniature devices

Problematic aspects of neodymium magnets and ways of using them

• 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 decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• They oxidize in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Limited ability of making nuts in the magnet and complicated forms - recommended is cover - magnetic holder.
• Possible danger related to microscopic parts of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. Furthermore, small components of these devices can disrupt the diagnostic process medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Highest magnetic holding force – what affects it?

The load parameter shown concerns the maximum value, measured under optimal environment, meaning:

• on a block made of structural steel, effectively closing the magnetic flux
• possessing a thickness of min. 10 mm to ensure full flux closure
• characterized by even structure
• without the slightest air gap between the magnet and steel
• during detachment in a direction vertical to the mounting surface
• at ambient temperature room level

What influences lifting capacity in practice

Effective lifting capacity is influenced by working environment parameters, such as (from priority):

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) significantly weakens the pulling force, often by half at just 0.5 mm.
• Direction of force – maximum parameter is reached only during pulling at a 90° angle. The shear force of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the power to be lost to the other side.
• Plate material – mild steel attracts best. Alloy admixtures lower magnetic properties and lifting capacity.
• Plate texture – smooth surfaces ensure maximum contact, which increases force. Uneven metal weaken the grip.
• Operating temperature – NdFeB sinters have a sensitivity to temperature. At higher temperatures they are weaker, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the load capacity is reduced by as much as 75%. Moreover, even a minimal clearance {between} the magnet’s surface and the plate reduces the holding force.