MW 8x20 / N38 - cylindrical magnet

Pros and cons of rare earth magnets.

Besides their magnetic performance, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (in laboratory conditions),
• Magnets very well protect themselves against loss of magnetization caused by foreign field sources,
• By covering with a lustrous coating of nickel, the element acquires an modern look,
• They are known for high magnetic induction at the operating surface, which improves attraction properties,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, allowing for operation at temperatures approaching 230°C and above...
• Possibility of exact machining and modifying to individual needs,
• Universal use in advanced technology sectors – they serve a role in computer drives, brushless drives, diagnostic systems, also other advanced devices.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets and ways of using them

• At strong impacts they can crack, therefore we advise 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 rust in a humid environment. For use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• We recommend cover - magnetic mechanism, due to difficulties in creating threads inside the magnet and complicated forms.
• Health risk to health – tiny shards of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small elements of these magnets can disrupt the diagnostic process medical when they are in the body.
• With large orders the cost of neodymium magnets is economically unviable,

Best holding force of the magnet in ideal parameters – what affects it?

The force parameter is a result of laboratory testing performed under specific, ideal conditions:

• on a block made of mild steel, perfectly concentrating the magnetic field
• possessing a massiveness of minimum 10 mm to avoid saturation
• with an polished touching surface
• without any air gap between the magnet and steel
• under axial force direction (90-degree angle)
• at temperature approx. 20 degrees Celsius

Practical lifting capacity: influencing factors

Bear in mind that the working load may be lower influenced by elements below, starting with the most relevant:

• Clearance – the presence of any layer (paint, dirt, air) acts as an insulator, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Angle of force application – maximum parameter is available only during perpendicular pulling. The shear force of the magnet along the surface is standardly many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Plate material – mild steel gives the best results. Alloy steels decrease magnetic properties and lifting capacity.
• Surface condition – smooth surfaces ensure maximum contact, which improves field saturation. Uneven metal reduce efficiency.
• Thermal conditions – NdFeB sinters have a sensitivity to temperature. When it is hot they lose power, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was carried out on a smooth plate of suitable thickness, under perpendicular forces, whereas under parallel forces the lifting capacity is smaller. In addition, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.