MW 8x15 / N38 - cylindrical magnet

Pros and cons of neodymium magnets.

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

• They virtually do not lose strength, because even after 10 years the performance loss is only ~1% (according to literature),
• Neodymium magnets are distinguished by exceptionally resistant to loss of magnetic properties caused by external magnetic fields,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to be more visually attractive,
• Magnets are distinguished by very high magnetic induction on the surface,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in constructing and the capacity to modify to unusual requirements,
• Fundamental importance in modern industrial fields – they are utilized in HDD drives, electromotive mechanisms, precision medical tools, as well as complex engineering applications.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also improves its resistance to damage
• 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
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material resistant to moisture
• We suggest a housing - magnetic mechanism, due to difficulties in creating nuts inside the magnet and complicated forms.
• Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which gains importance in the context of child safety. Furthermore, tiny parts of these products can be problematic in diagnostics medical when they are in the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Maximum holding power of the magnet – what affects it?

Magnet power was determined for ideal contact conditions, including:

• with the application of a yoke made of special test steel, ensuring maximum field concentration
• whose transverse dimension is min. 10 mm
• with an ground touching surface
• with total lack of distance (no paint)
• during pulling in a direction vertical to the mounting surface
• at standard ambient temperature

Practical aspects of lifting capacity – factors

In real-world applications, the actual holding force results from several key aspects, ranked from crucial:

• Distance – existence of any layer (paint, dirt, air) interrupts the magnetic circuit, which reduces power steeply (even by 50% at 0.5 mm).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. High carbon content worsen the interaction with the magnet.
• Surface condition – smooth surfaces guarantee perfect abutment, which increases force. Uneven metal reduce efficiency.
• Temperature – temperature increase results in weakening of induction. Check the maximum operating temperature for a given model.

* Lifting capacity testing was performed on a smooth plate of suitable thickness, under a perpendicular pulling force, in contrast under shearing force the load capacity is reduced by as much as 75%. Additionally, even a small distance {between} the magnet’s surface and the plate lowers the lifting capacity.