ZM XMAG2 210 elementów - magnetic toy

Advantages and disadvantages of rare earth magnets.

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

• Their strength remains stable, and after around ten years it drops only by ~1% (according to research),
• Neodymium magnets are remarkably resistant to magnetic field loss caused by external interference,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to look better,
• Magnets have exceptionally strong magnetic induction on the outer layer,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate modeling as well as adapting to defined requirements,
• Fundamental importance in high-tech industry – they are utilized in mass storage devices, brushless drives, advanced medical instruments, also other advanced devices.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in small dimensions, which enables their usage in small systems

Problematic aspects of neodymium magnets and ways of using them

• Brittleness is one of their disadvantages. Upon strong impact they can fracture. We recommend keeping them in a strong case, which not only protects them against impacts but also raises their durability
• Neodymium magnets lose their power 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
• When exposed to humidity, magnets usually rust. To use them in conditions outside, it is recommended to use protective magnets, such as magnets in rubber or plastics, which prevent oxidation and corrosion.
• Due to limitations in realizing threads and complex shapes in magnets, we recommend using casing - magnetic holder.
• Possible danger resulting from small fragments of magnets are risky, if swallowed, which is particularly important in the context of child safety. Additionally, tiny parts of these products can disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

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

Magnet power was defined for ideal contact conditions, including:

• with the use of a sheet made of special test steel, ensuring full magnetic saturation
• with a thickness minimum 10 mm
• with a surface free of scratches
• without any insulating layer between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• in stable room temperature

Impact of factors on magnetic holding capacity in practice

Holding efficiency impacted by working environment parameters, mainly (from priority):

• Distance – existence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Load vector – maximum parameter is reached only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is standardly several times lower (approx. 1/5 of the lifting capacity).
• Steel thickness – too thin steel does not close the flux, causing part of the flux to be escaped to the other side.
• Plate material – low-carbon steel attracts best. Alloy steels lower magnetic permeability and lifting capacity.
• Surface quality – the smoother and more polished the plate, the better the adhesion and stronger the hold. Roughness creates an air distance.
• Operating temperature – neodymium magnets have a negative temperature coefficient. At higher temperatures they lose power, and in frost they can be stronger (up to a certain limit).

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Moreover, even a slight gap {between} the magnet and the plate lowers the lifting capacity.