MW 9x3 / N38 - cylindrical magnet

Advantages and disadvantages of NdFeB magnets.

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

• They virtually do not lose power, because even after 10 years the decline in efficiency is only ~1% (based on calculations),
• Magnets very well defend themselves against loss of magnetization caused by ambient magnetic noise,
• In other words, due to the shiny finish of gold, the element gains a professional look,
• The surface of neodymium magnets generates a intense magnetic field – this is a distinguishing feature,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, enabling action at temperatures approaching 230°C and above...
• Possibility of precise machining and optimizing to individual requirements,
• Universal use in advanced technology sectors – they are utilized in HDD drives, drive modules, medical equipment, also technologically advanced constructions.
• Relatively small size with high pulling force – neodymium magnets offer high power in tiny dimensions, which enables their usage in small systems

Disadvantages of NdFeB magnets:

• At strong impacts they can break, therefore we advise placing them in special holders. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets demagnetize when exposed to high temperatures. After reaching 80°C, many of them experience permanent weakening of power (a factor is the shape and dimensions of the magnet). We offer magnets specially adapted to work at temperatures up to 230°C marked [AH], which are extremely resistant to heat
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, when using outdoors
• Limited possibility of making threads in the magnet and complicated forms - recommended is a housing - magnet mounting.
• Possible danger to health – tiny shards of magnets are risky, if swallowed, which gains importance in the context of child safety. Additionally, tiny parts of these devices are able to be problematic in diagnostics medical after entering the body.
• With large orders the cost of neodymium magnets is a challenge,

Maximum lifting capacity of the magnet – what affects it?

The declared magnet strength concerns the maximum value, obtained under optimal environment, meaning:

• using a plate made of mild steel, acting as a circuit closing element
• possessing a thickness of min. 10 mm to ensure full flux closure
• with an ideally smooth contact surface
• under conditions of ideal adhesion (surface-to-surface)
• under axial application of breakaway force (90-degree angle)
• in neutral thermal conditions

Key elements affecting lifting force

In real-world applications, the real power is determined by several key aspects, listed from crucial:

• Clearance – existence of foreign body (rust, tape, gap) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is reached only during perpendicular pulling. The force required to slide of the magnet along the plate is usually many times smaller (approx. 1/5 of the lifting capacity).
• Wall thickness – thin material does not allow full use of the magnet. Magnetic flux passes through the material instead of generating force.
• Material type – ideal substrate is pure iron steel. Cast iron may attract less.
• Surface quality – the smoother and more polished the plate, the larger the contact zone and stronger the hold. Roughness acts like micro-gaps.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Lifting capacity was assessed by applying a smooth steel plate of suitable thickness (min. 20 mm), under perpendicular pulling force, whereas under shearing force the holding force is lower. Moreover, even a slight gap {between} the magnet and the plate lowers the lifting capacity.