ZM XMAG2 105 elementów - magnetic toy

Advantages and disadvantages of rare earth magnets.

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

• They have constant strength, and over around 10 years their performance decreases symbolically – ~1% (according to theory),
• They retain their magnetic properties even under strong external field,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to look better,
• The surface of neodymium magnets generates a concentrated magnetic field – this is one of their assets,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Possibility of detailed machining and optimizing to concrete conditions,
• Key role in modern technologies – they find application in hard drives, electric drive systems, precision medical tools, as well as other advanced devices.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

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

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in strength. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• They oxidize in a humid environment - during use outdoors we recommend 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 are risky, if swallowed, which is particularly important in the context of child health protection. Furthermore, small elements of these products are able to disrupt the diagnostic process medical when they are in the body.
• Due to expensive raw materials, their price is higher than average,

Maximum magnetic pulling force – what contributes to it?

Breakaway force was defined for ideal contact conditions, including:

• with the contact of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• with a thickness of at least 10 mm
• with an ground touching surface
• with zero gap (without paint)
• during pulling in a direction vertical to the mounting surface
• at room temperature

Lifting capacity in real conditions – factors

In practice, the actual lifting capacity results from several key aspects, presented from crucial:

• Clearance – the presence of foreign body (rust, tape, gap) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Loading method – catalog parameter refers to pulling vertically. When attempting to slide, the magnet exhibits significantly lower power (typically approx. 20-30% of maximum force).
• Wall thickness – the thinner the sheet, the weaker the hold. Magnetic flux penetrates through instead of converting into lifting capacity.
• Steel type – mild steel gives the best results. Alloy steels decrease magnetic permeability and lifting capacity.
• Smoothness – full contact is possible only on polished steel. Rough texture create air cushions, reducing force.
• Temperature – temperature increase results in weakening of induction. It is worth remembering the thermal limit for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas 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 holding force.