MP 12x8/4x3 / N38 - ring magnet

Pros as well as cons of rare earth magnets.

Apart from their consistent power, neodymium magnets have these key benefits:

• They have constant strength, and over around ten years their attraction force decreases symbolically – ~1% (in testing),
• Neodymium magnets are remarkably resistant to loss of magnetic properties caused by external interference,
• In other words, due to the metallic layer of nickel, the element looks attractive,
• The surface of neodymium magnets generates a strong magnetic field – this is a key feature,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Due to the possibility of precise molding and customization to individualized requirements, NdFeB magnets can be created in a variety of shapes and sizes, which amplifies use scope,
• Versatile presence in high-tech industry – they are used in HDD drives, electric motors, advanced medical instruments, and technologically advanced constructions.
• Thanks to concentrated force, small magnets offer high operating force, with minimal size,

Disadvantages of neodymium magnets:

• To avoid cracks upon strong impacts, we suggest using special steel housings. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and 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 when using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We recommend cover - magnetic mechanism, due to difficulties in realizing 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 health protection. Furthermore, small elements of these magnets can be problematic in diagnostics medical when they are in the body.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum magnetic pulling force – what affects it?

The specified lifting capacity refers to the peak performance, obtained under laboratory conditions, meaning:

• with the application of a sheet made of special test steel, ensuring maximum field concentration
• possessing a massiveness of at least 10 mm to ensure full flux closure
• characterized by smoothness
• under conditions of gap-free contact (metal-to-metal)
• during pulling in a direction vertical to the mounting surface
• at conditions approx. 20°C

Impact of factors on magnetic holding capacity in practice

In real-world applications, the actual lifting capacity results from a number of factors, listed from crucial:

• Gap between magnet and steel – every millimeter of distance (caused e.g. by varnish or unevenness) diminishes the pulling force, often by half at just 0.5 mm.
• Loading method – declared lifting capacity refers to detachment vertically. When attempting to slide, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Metal thickness – thin material does not allow full use of the magnet. Part of the magnetic field passes through the material instead of generating force.
• Material type – ideal substrate is pure iron steel. Hardened steels may have worse magnetic properties.
• Smoothness – full contact is obtained only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
• Temperature – heating the magnet results in weakening of force. It is worth remembering the thermal limit for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the load capacity.