SMZR 25x150 / N52 - magnetic separator with handle

Advantages as well as disadvantages of NdFeB magnets.

Besides their immense field intensity, neodymium magnets offer the following advantages:

• Their magnetic field remains stable, and after approximately ten years it drops only by ~1% (according to research),
• Magnets effectively protect themselves against demagnetization caused by external fields,
• Thanks to the shimmering finish, the coating of nickel, gold, or silver gives an clean appearance,
• Neodymium magnets achieve maximum magnetic induction on a contact point, which increases force concentration,
• 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...
• Possibility of individual forming as well as modifying to specific needs,
• Key role in high-tech industry – they find application in computer drives, brushless drives, advanced medical instruments, as well as complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in compact dimensions, which allows their use in miniature devices

Disadvantages of neodymium magnets:

• Brittleness is one of their disadvantages. Upon intense impact they can fracture. We advise keeping them in a steel housing, which not only protects them against impacts but also increases 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 force. 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 recommend using waterproof magnets e.g. in rubber, plastic
• Due to limitations in realizing threads and complex shapes in magnets, we recommend using cover - magnetic mechanism.
• Possible danger resulting from small fragments of magnets are risky, if swallowed, which is particularly important in the context of child health protection. It is also worth noting that tiny parts of these products can disrupt the diagnostic process medical in case of swallowing.
• With budget limitations the cost of neodymium magnets is economically unviable,

Maximum lifting capacity of the magnet – what it depends on?

The force parameter is a measurement result performed under specific, ideal conditions:

• using a sheet made of mild steel, acting as a magnetic yoke
• whose thickness is min. 10 mm
• with a surface cleaned and smooth
• under conditions of ideal adhesion (metal-to-metal)
• for force applied at a right angle (in the magnet axis)
• at temperature approx. 20 degrees Celsius

Impact of factors on magnetic holding capacity in practice

In practice, the real power depends on many variables, listed from crucial:

• Gap (between the magnet and the metal), because even a tiny clearance (e.g. 0.5 mm) can cause a decrease in lifting capacity by up to 50% (this also applies to varnish, rust or debris).
• Loading method – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet holds significantly lower power (often approx. 20-30% of nominal force).
• Element thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice is pure iron steel. Hardened steels may have worse magnetic properties.
• Plate texture – smooth surfaces guarantee perfect abutment, which increases field saturation. Rough surfaces reduce efficiency.
• Thermal conditions – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost gain strength (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of optimal thickness, under a perpendicular pulling force, in contrast under attempts to slide the magnet the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.