MW 38x3.5 / N38 - cylindrical magnet

Pros as well as cons of neodymium magnets.

In addition to their long-term stability, neodymium magnets provide the following advantages:

• They do not lose magnetism, even over around ten years – the drop in lifting capacity is only ~1% (theoretically),
• Magnets very well resist against demagnetization caused by ambient magnetic noise,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets deliver maximum magnetic induction on a small surface, which ensures high operational effectiveness,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can function (depending on the form) even at a temperature of 230°C or more...
• Possibility of exact shaping and optimizing to complex conditions,
• Wide application in innovative solutions – they are utilized in hard drives, electromotive mechanisms, advanced medical instruments, also complex engineering applications.
• Relatively small size with high pulling force – neodymium magnets offer strong magnetic field in tiny dimensions, which makes them useful in miniature devices

Disadvantages of NdFeB 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 protects the magnet but also improves 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 durability 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 possibility of making threads in the magnet and complicated forms - recommended is cover - magnetic holder.
• Potential hazard to health – tiny shards of magnets are risky, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Furthermore, small elements of these products are able to be problematic in diagnostics medical when they are in the body.
• Due to neodymium price, their price is higher than average,

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

Breakaway force was defined for the most favorable conditions, including:

• using a plate made of low-carbon steel, acting as a circuit closing element
• whose transverse dimension is min. 10 mm
• with a surface perfectly flat
• with total lack of distance (no coatings)
• during detachment in a direction perpendicular to the plane
• at ambient temperature approx. 20 degrees Celsius

Lifting capacity in practice – influencing factors

During everyday use, the actual holding force is determined by many variables, listed from most significant:

• Gap between surfaces – even a fraction of a millimeter of separation (caused e.g. by veneer or dirt) drastically reduces the pulling force, often by half at just 0.5 mm.
• Pull-off angle – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Wall thickness – the thinner the sheet, the weaker the hold. Part of the magnetic field penetrates through instead of converting into lifting capacity.
• Metal type – different alloys reacts the same. Alloy additives worsen the interaction with the magnet.
• Plate texture – smooth surfaces ensure maximum contact, which increases field saturation. Rough surfaces reduce efficiency.
• Heat – neodymium magnets have a sensitivity to temperature. When it is hot they lose power, and at low temperatures they can be stronger (up to a certain limit).

* Lifting capacity was assessed by applying a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.