MW 8x20 / N38 - cylindrical magnet

Strengths and weaknesses of neodymium magnets.

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

• They do not lose strength, even over around ten years – the decrease in power is only ~1% (based on measurements),
• Magnets very well protect themselves against demagnetization caused by external fields,
• By applying a lustrous layer of silver, the element acquires an elegant look,
• Neodymium magnets ensure maximum magnetic induction on a contact point, which increases force concentration,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to flexibility in forming and the capacity to modify to unusual requirements,
• Huge importance in modern industrial fields – they are commonly used in HDD drives, electric drive systems, medical equipment, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in compact dimensions, which makes them useful in miniature devices

Disadvantages of neodymium magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth protecting magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material stable to moisture, when using outdoors
• Due to limitations in producing nuts and complicated forms in magnets, we recommend using cover - magnetic mount.
• Possible danger to health – tiny shards of magnets are risky, in case of ingestion, which gains importance in the context of child health protection. Furthermore, small components of these products are able to disrupt the diagnostic process medical when they are in the body.
• With large orders the cost of neodymium magnets is a challenge,

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

The lifting capacity listed is a theoretical maximum value executed under standard conditions:

• using a sheet made of mild steel, acting as a circuit closing element
• whose transverse dimension equals approx. 10 mm
• with an ideally smooth contact surface
• with zero gap (no impurities)
• under perpendicular force vector (90-degree angle)
• in stable room temperature

Impact of factors on magnetic holding capacity in practice

Bear in mind that the working load will differ subject to the following factors, starting with the most relevant:

• Space between magnet and steel – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) significantly weakens the pulling force, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to detachment vertically. When applying parallel force, the magnet holds much less (typically approx. 20-30% of maximum force).
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field passes through the material instead of converting into lifting capacity.
• Material type – ideal substrate is pure iron steel. Stainless steels may generate lower lifting capacity.
• Surface quality – the more even the plate, the better the adhesion and higher the lifting capacity. Unevenness acts like micro-gaps.
• Thermal environment – heating the magnet causes a temporary drop of force. It is worth remembering the maximum operating temperature for a given model.

* Holding force was measured on the plate surface of 20 mm thickness, when a perpendicular force was applied, in contrast under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate decreases the holding force.