SMZR 25x100 / N52 - magnetic separator with handle

Pros and cons of NdFeB magnets.

Besides their immense magnetic power, neodymium magnets offer the following advantages:

• They do not lose strength, even after nearly ten years – the reduction in strength is only ~1% (theoretically),
• They are resistant to demagnetization induced by external magnetic fields,
• By applying a smooth coating of silver, the element acquires an modern look,
• Magnets have excellent magnetic induction on the outer side,
• 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 shaping and the capacity to modify to unusual requirements,
• Huge importance in modern industrial fields – they find application in mass storage devices, electromotive mechanisms, advanced medical instruments, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in compact dimensions, which makes them useful in miniature devices

Cons of neodymium magnets: weaknesses and usage proposals

• At strong impacts they can break, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets decrease their strength 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
• They oxidize in a humid environment - during use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited ability of creating nuts in the magnet and complex shapes - recommended is cover - magnet mounting.
• Potential hazard related to microscopic parts of magnets pose a threat, in case of ingestion, which is particularly important in the context of child health protection. Additionally, small components of these magnets are able to complicate diagnosis medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which increases costs of application in large quantities

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

The lifting capacity listed is a result of laboratory testing executed under the following configuration:

• on a plate made of structural steel, effectively closing the magnetic flux
• with a cross-section of at least 10 mm
• with a plane cleaned and smooth
• under conditions of no distance (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at ambient temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

Bear in mind that the magnet holding will differ depending on the following factors, starting with the most relevant:

• Space between magnet and steel – every millimeter of distance (caused e.g. by veneer or dirt) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Pull-off angle – remember that the magnet has greatest strength perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the maximum value.
• Base massiveness – insufficiently thick steel does not accept the full field, causing part of the power to be escaped into the air.
• Plate material – low-carbon steel gives the best results. Alloy admixtures decrease magnetic permeability and lifting capacity.
• Surface structure – the more even the plate, the better the adhesion and stronger the hold. Unevenness acts like micro-gaps.
• Thermal factor – high temperature reduces pulling force. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under perpendicular forces, however under shearing force the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate reduces the lifting capacity.