MW 10x10 / N38 - cylindrical magnet

Strengths as well as weaknesses of neodymium magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• Their strength is maintained, and after around 10 years it decreases only by ~1% (theoretically),
• They show high resistance to demagnetization induced by presence of other magnetic fields,
• The use of an shiny coating of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets generate 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 are able to act (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate modeling and optimizing to atypical needs,
• Significant place in innovative solutions – they are utilized in mass storage devices, electromotive mechanisms, medical equipment, also modern systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• They are prone to damage upon heavy impacts. To avoid cracks, it is worth securing magnets in special housings. Such protection not only shields the magnet but also increases its resistance to damage
• Neodymium magnets lose strength when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of strength (a factor is the shape as well as dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are very resistant to heat
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• We recommend a housing - magnetic mechanism, due to difficulties in producing threads inside the magnet and complex forms.
• Health risk 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 devices can be problematic in diagnostics medical in case of swallowing.
• High unit price – neodymium magnets have a higher price than other types of magnets (e.g. ferrite), which hinders application in large quantities

Highest magnetic holding force – what it depends on?

The declared magnet strength concerns the peak performance, recorded under laboratory conditions, namely:

• using a sheet made of mild steel, functioning as a magnetic yoke
• whose transverse dimension is min. 10 mm
• characterized by lack of roughness
• under conditions of gap-free contact (metal-to-metal)
• under perpendicular force direction (90-degree angle)
• at conditions approx. 20°C

Practical lifting capacity: influencing factors

Holding efficiency is affected by working environment parameters, such as (from priority):

• Space between magnet and steel – even a fraction of a millimeter of distance (caused e.g. by varnish or dirt) diminishes the pulling force, often by half at just 0.5 mm.
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the plate is typically many times lower (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux penetrates through instead of generating force.
• Material composition – not every steel attracts identically. High carbon content weaken the interaction with the magnet.
• Surface structure – the smoother and more polished the surface, the better the adhesion and higher the lifting capacity. Roughness acts like micro-gaps.
• Thermal environment – heating the magnet results in weakening of induction. Check the thermal limit for a given model.

* Holding force was tested on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, however under parallel forces the lifting capacity is smaller. Moreover, even a minimal clearance {between} the magnet and the plate decreases the lifting capacity.