SMZR 25x175 / N52 - magnetic separator with handle

Pros and cons of neodymium magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• Their magnetic field is durable, and after around 10 years it decreases only by ~1% (theoretically),
• They show high resistance to demagnetization induced by presence of other magnetic fields,
• Thanks to the smooth finish, the surface of Ni-Cu-Ni, gold-plated, or silver-plated gives an elegant appearance,
• The surface of neodymium magnets generates a unique magnetic field – this is a key feature,
• 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 forming and the ability to adapt to unusual requirements,
• Key role in modern industrial fields – they serve a role in magnetic memories, drive modules, medical devices, also modern systems.
• Thanks to their power density, small magnets offer high operating force, occupying minimum space,

Problematic aspects of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets suffer a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as those in rubber or plastics, which secure oxidation and corrosion.
• Limited possibility of making threads in the magnet and complicated shapes - preferred is a housing - magnetic holder.
• Possible danger resulting from small fragments of magnets can be dangerous, if swallowed, which gains importance in the aspect of protecting the youngest. It is also worth noting that tiny parts of these devices can be problematic in diagnostics medical when they are in the body.
• With large orders the cost of neodymium magnets is economically unviable,

Magnetic strength at its maximum – what it depends on?

The specified lifting capacity refers to the peak performance, measured under ideal test conditions, namely:

• on a plate made of mild steel, effectively closing the magnetic flux
• with a thickness no less than 10 mm
• with a surface free of scratches
• with total lack of distance (no coatings)
• under vertical force vector (90-degree angle)
• at temperature approx. 20 degrees Celsius

Determinants of lifting force in real conditions

Effective lifting capacity is influenced by working environment parameters, mainly (from most important):

• Clearance – the presence of foreign body (paint, dirt, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of nominal force).
• Metal thickness – the thinner the sheet, the weaker the hold. Magnetic flux passes through the material instead of generating force.
• Material composition – different alloys reacts the same. High carbon content worsen the attraction effect.
• Surface finish – full contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment weakens magnetic field. Too high temperature can permanently demagnetize the magnet.

* Holding force was tested on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under shearing force the holding force is lower. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the lifting capacity.