UMH 32x8x46 [M6] / N38 - magnetic holder with hook

Advantages as well as disadvantages of rare earth magnets.

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

• They retain full power for around 10 years – the loss is just ~1% (in theory),
• They are noted for resistance to demagnetization induced by presence of other magnetic fields,
• By applying a shiny coating of nickel, the element presents an professional look,
• Magnetic induction on the surface of the magnet is maximum,
• Through (adequate) combination of ingredients, they can achieve high thermal strength, allowing for action at temperatures reaching 230°C and above...
• Possibility of accurate modeling as well as modifying to concrete applications,
• Key role in modern technologies – they find application in HDD drives, brushless drives, precision medical tools, also industrial machines.
• Relatively small size with high pulling force – neodymium magnets offer impressive pulling force in tiny dimensions, which makes them useful in miniature devices

Problematic aspects of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a special holder, which not only protects them against impacts but also raises their durability
• When exposed to high temperature, neodymium magnets suffer a drop in force. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we suggest using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in producing nuts and complex shapes in magnets, we propose using a housing - magnetic mount.
• Possible danger related to microscopic parts of magnets pose a threat, when accidentally swallowed, which gains importance in the aspect of protecting the youngest. Additionally, tiny parts of these magnets are able to be problematic in diagnostics medical after entering the body.
• Due to complex production process, their price exceeds standard values,

Maximum magnetic pulling force – what contributes to it?

The load parameter shown refers to the limit force, measured under optimal environment, meaning:

• with the use of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• possessing a massiveness of min. 10 mm to ensure full flux closure
• with a plane perfectly flat
• without the slightest clearance between the magnet and steel
• for force acting at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Key elements affecting lifting force

Real force is affected by specific conditions, including (from priority):

• Space between surfaces – even a fraction of a millimeter of distance (caused e.g. by varnish or unevenness) drastically reduces the magnet efficiency, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When applying parallel force, the magnet exhibits significantly lower power (often approx. 20-30% of maximum force).
• Steel thickness – too thin steel does not accept the full field, causing part of the flux to be wasted into the air.
• Metal type – not every steel reacts the same. Alloy additives worsen the interaction with the magnet.
• Smoothness – full contact is possible only on polished steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity testing was performed on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, in contrast under parallel forces the load capacity is reduced by as much as 5 times. Moreover, even a small distance {between} the magnet and the plate decreases the holding force.