SM 25x125 [2xM8] / N52 - magnetic separator

Strengths and weaknesses of rare earth magnets.

Apart from their strong magnetic energy, neodymium magnets have these key benefits:

• They do not lose power, even after nearly 10 years – the drop in strength is only ~1% (theoretically),
• Neodymium magnets prove to be exceptionally resistant to loss of magnetic properties caused by external interference,
• Thanks to the metallic finish, the layer of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• Magnets are characterized by extremely high magnetic induction on the outer side,
• 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...
• Thanks to modularity in constructing and the capacity to modify to unusual requirements,
• Huge importance in future technologies – they find application in computer drives, drive modules, medical equipment, and modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we recommend using special steel housings. Such a solution secures the magnet and simultaneously increases its durability.
• Neodymium magnets decrease their power 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 stability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• Limited ability of creating nuts in the magnet and complicated forms - preferred is casing - magnetic holder.
• Potential hazard resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the context of child safety. Furthermore, tiny parts of these devices are able to be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

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

The declared magnet strength refers to the peak performance, recorded under optimal environment, namely:

• on a base made of mild steel, effectively closing the magnetic field
• with a cross-section no less than 10 mm
• with a plane perfectly flat
• without the slightest clearance between the magnet and steel
• under perpendicular force direction (90-degree angle)
• at conditions approx. 20°C

Determinants of lifting force in real conditions

Holding efficiency is affected by specific conditions, mainly (from most important):

• Clearance – the presence of any layer (paint, dirt, air) acts as an insulator, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of maximum force).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Plate material – low-carbon steel gives the best results. Higher carbon content lower magnetic properties and holding force.
• Surface quality – the smoother and more polished the plate, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Temperature – temperature increase causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Lifting capacity was determined by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, whereas under parallel forces the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.