SMZR 25x200 / N52 - magnetic separator with handle

Pros as well as cons of neodymium magnets.

Apart from their superior power, neodymium magnets have these key benefits:

• They do not lose strength, even after nearly 10 years – the drop in strength is only ~1% (theoretically),
• They are noted for resistance to demagnetization induced by external field influence,
• The use of an aesthetic coating of noble metals (nickel, gold, silver) causes the element to look better,
• Magnetic induction on the surface of the magnet is strong,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their shape) at temperatures up to 230°C and above...
• In view of the possibility of precise shaping and customization to specialized projects, magnetic components can be manufactured in a broad palette of geometric configurations, which makes them more universal,
• Universal use in advanced technology sectors – they serve a role in HDD drives, brushless drives, precision medical tools, as well as technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, in miniature format,

Characteristics of disadvantages of neodymium magnets and proposals for their use:

• Brittleness is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose 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
• When exposed to humidity, magnets usually rust. For applications outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which secure oxidation and corrosion.
• We suggest a housing - magnetic mechanism, due to difficulties in creating threads inside the magnet and complex forms.
• Possible danger to health – tiny shards of magnets are risky, in case of ingestion, which becomes key in the aspect of protecting the youngest. Furthermore, tiny parts of these magnets can be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which hinders application in large quantities

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

Information about lifting capacity is the result of a measurement for ideal contact conditions, including:

• with the contact of a yoke made of low-carbon steel, ensuring maximum field concentration
• whose thickness reaches at least 10 mm
• with a plane free of scratches
• without any air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• in temp. approx. 20°C

Magnet lifting force in use – key factors

Please note that the application force will differ subject to the following factors, starting with the most relevant:

• Clearance – existence of any layer (rust, tape, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is reached only during pulling at a 90° angle. The force required to slide of the magnet along the plate is usually several times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys attracts identically. High carbon content worsen the attraction effect.
• Surface finish – full contact is possible only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment weakens magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity was determined by applying a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the holding force is lower. In addition, even a slight gap {between} the magnet and the plate lowers the holding force.