MW 24x6 / N38 - cylindrical magnet

Pros as well as cons of rare earth magnets.

Besides their immense field intensity, neodymium magnets offer the following advantages:

• They retain attractive force for almost 10 years – the loss is just ~1% (based on simulations),
• They feature excellent resistance to magnetism drop due to opposing magnetic fields,
• By applying a reflective coating of silver, the element gains an modern look,
• They show high magnetic induction at the operating surface, making them more effective,
• Neodymium magnets are known for very high magnetic induction and the ability to work at temperatures up to 230°C or higher (depending on the geometry),
• Possibility of individual creating as well as adapting to concrete applications,
• Fundamental importance in high-tech industry – they are utilized in HDD drives, drive modules, precision medical tools, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• They are fragile upon too strong impacts. To avoid cracks, it is worth securing magnets using a steel holder. Such protection not only shields the magnet but also increases its resistance to damage
• 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 - during use outdoors we recommend using waterproof magnets e.g. in rubber, plastic
• Limited ability of making nuts in the magnet and complex shapes - preferred is casing - magnet mounting.
• Potential hazard related to microscopic parts of magnets are risky, when accidentally swallowed, which gains importance in the context of child safety. Furthermore, small elements of these devices are able to complicate diagnosis medical when they are in the body.
• High unit price – neodymium magnets cost more than other types of magnets (e.g. ferrite), which can limit application in large quantities

Detachment force of the magnet in optimal conditions – what it depends on?

The declared magnet strength refers to the maximum value, obtained under laboratory conditions, namely:

• with the application of a sheet made of special test steel, guaranteeing full magnetic saturation
• with a cross-section of at least 10 mm
• with a surface free of scratches
• with direct contact (no impurities)
• under axial force direction (90-degree angle)
• at room temperature

Practical lifting capacity: influencing factors

During everyday use, the real power depends on a number of factors, listed from crucial:

• Air gap (betwixt the magnet and the plate), as even a microscopic distance (e.g. 0.5 mm) can cause a drastic drop in force by up to 50% (this also applies to varnish, corrosion or debris).
• Loading method – declared lifting capacity refers to pulling vertically. When slipping, the magnet holds much less (typically approx. 20-30% of nominal force).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys attracts identically. High carbon content weaken the attraction effect.
• Surface quality – the more even the surface, the larger the contact zone and higher the lifting capacity. Unevenness acts like micro-gaps.
• Thermal conditions – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Lifting capacity was determined by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under shearing force the holding force is lower. In addition, even a small distance {between} the magnet and the plate decreases the load capacity.