SM 32x175 [2xM8] / N52 - magnetic separator

Advantages and disadvantages of neodymium magnets.

Besides their remarkable pulling force, neodymium magnets offer the following advantages:

• They have unchanged lifting capacity, and over around ten years their attraction force decreases symbolically – ~1% (according to theory),
• Magnets effectively defend themselves against demagnetization caused by ambient magnetic noise,
• By covering with a decorative coating of nickel, the element presents an nice look,
• They show high magnetic induction at the operating surface, which improves attraction properties,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to modularity in constructing and the ability to modify to client solutions,
• Huge importance in modern industrial fields – they are utilized in magnetic memories, motor assemblies, diagnostic systems, as well as industrial machines.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Problematic aspects of neodymium magnets: application proposals

• To avoid cracks under impact, we suggest 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 force. 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 advise using waterproof magnets made of rubber, plastic or other material resistant to moisture, when using outdoors
• We recommend a housing - magnetic mount, due to difficulties in creating threads inside the magnet and complicated forms.
• Health risk resulting from small fragments of magnets are risky, if swallowed, which gains importance in the context of child safety. Additionally, small components of these products are able to disrupt the diagnostic process medical after entering the body.
• With large orders the cost of neodymium magnets is economically unviable,

Maximum magnetic pulling force – what affects it?

Breakaway force was determined for optimal configuration, including:

• on a base made of mild steel, optimally conducting the magnetic flux
• whose transverse dimension equals approx. 10 mm
• characterized by even structure
• under conditions of no distance (metal-to-metal)
• for force applied at a right angle (in the magnet axis)
• in neutral thermal conditions

Practical aspects of lifting capacity – factors

In real-world applications, the actual lifting capacity depends on a number of factors, ranked from crucial:

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by varnish or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds significantly lower power (often approx. 20-30% of maximum force).
• Plate thickness – insufficiently thick steel does not accept the full field, causing part of the power to be wasted to the other side.
• Steel grade – ideal substrate is pure iron steel. Cast iron may attract less.
• Surface quality – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness creates an air distance.
• Thermal environment – heating the magnet causes a temporary drop of force. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, in contrast under shearing force the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the load capacity.