ZM XMAG2 105 elementów - magnetic toy

Advantages as well as disadvantages of NdFeB magnets.

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

• They have constant strength, and over nearly 10 years their attraction force decreases symbolically – ~1% (according to theory),
• Neodymium magnets are characterized by extremely resistant to loss of magnetic properties caused by external magnetic fields,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to present itself better,
• The surface of neodymium magnets generates a maximum magnetic field – this is one of their assets,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, enabling functioning at temperatures reaching 230°C and above...
• Thanks to flexibility in constructing and the ability to customize to unusual requirements,
• Key role in future technologies – they are utilized in HDD drives, electric motors, diagnostic systems, and modern systems.
• Thanks to efficiency per cm³, small magnets offer high operating force, occupying minimum space,

Disadvantages of neodymium magnets:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a steel housing, which not only protects them against impacts but also raises their durability
• We warn that neodymium magnets can lose their power at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material resistant to moisture
• Limited ability of making nuts in the magnet and complex shapes - recommended is a housing - magnetic holder.
• Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which becomes key in the aspect of protecting the youngest. It is also worth noting that tiny parts of these magnets are able to be problematic in diagnostics medical in case of swallowing.
• Due to complex production process, their price is relatively high,

Maximum holding power of the magnet – what affects it?

Information about lifting capacity was defined for ideal contact conditions, taking into account:

• with the use of a sheet made of special test steel, ensuring maximum field concentration
• possessing a thickness of at least 10 mm to ensure full flux closure
• with an ideally smooth contact surface
• without the slightest insulating layer between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• in stable room temperature

Key elements affecting lifting force

During everyday use, the actual holding force is determined by a number of factors, ranked from crucial:

• Air gap (betwixt the magnet and the plate), because even a microscopic distance (e.g. 0.5 mm) can cause a drastic drop in lifting capacity by up to 50% (this also applies to paint, corrosion or dirt).
• Pull-off angle – remember that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – to utilize 100% power, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Steel grade – ideal substrate is pure iron steel. Hardened steels may generate lower lifting capacity.
• Smoothness – ideal contact is obtained only on smooth steel. Rough texture create air cushions, reducing force.
• Temperature – heating the magnet results in weakening of induction. It is worth remembering the thermal limit for a given model.

* Lifting capacity was assessed by applying a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 5 times. In addition, even a minimal clearance {between} the magnet and the plate decreases the load capacity.