MW 15x3 / N38 - cylindrical magnet

Advantages as well as disadvantages of rare earth magnets.

Besides their exceptional magnetic power, neodymium magnets offer the following advantages:

• They retain full power for nearly 10 years – the loss is just ~1% (based on simulations),
• They possess excellent resistance to magnetism drop as a result of external fields,
• A magnet with a shiny nickel surface looks better,
• Magnetic induction on the working part of the magnet turns out to be maximum,
• Due to their durability and thermal resistance, neodymium magnets can operate (depending on the shape) even at high temperatures reaching 230°C or more...
• Thanks to the option of accurate molding and adaptation to specialized requirements, magnetic components can be produced in a wide range of forms and dimensions, which increases their versatility,
• Key role in future technologies – they serve a role in mass storage devices, drive modules, diagnostic systems, as well as modern systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which enables their usage in miniature devices

Problematic aspects of neodymium magnets: weaknesses and usage proposals

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can break. We advise keeping them in a steel housing, which not only secures 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 power 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
• They oxidize in a humid environment. For use outdoors we suggest using waterproof magnets e.g. in rubber, plastic
• Limited ability of creating threads in the magnet and complex shapes - preferred is a housing - mounting mechanism.
• Health risk related to microscopic parts of magnets are risky, if swallowed, which gains importance in the context of child safety. Additionally, tiny parts of these magnets can disrupt the diagnostic process medical when they are in the body.
• Due to neodymium price, their price is higher than average,

Maximum lifting capacity of the magnet – what affects it?

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

• with the use of a sheet made of special test steel, guaranteeing full magnetic saturation
• whose thickness is min. 10 mm
• with a plane free of scratches
• without any clearance between the magnet and steel
• for force applied at a right angle (in the magnet axis)
• in stable room temperature

Key elements affecting lifting force

Holding efficiency is influenced by specific conditions, such as (from most important):

• Gap 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.
• Angle of force application – maximum parameter is available only during pulling at a 90° angle. The shear force of the magnet along the plate is typically several times smaller (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal restricts the attraction force (the magnet "punches through" it).
• Plate material – mild steel attracts best. Higher carbon content decrease magnetic permeability and holding force.
• Surface quality – the more even the plate, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Temperature – temperature increase causes a temporary drop of induction. Check the thermal limit for a given model.

* Holding force was tested on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet’s surface and the plate reduces the load capacity.