MW 15x4 / N38 - cylindrical magnet

Advantages as well as disadvantages of neodymium magnets.

Apart from their notable magnetic energy, neodymium magnets have these key benefits:

• They do not lose strength, even after around ten years – the decrease in lifting capacity is only ~1% (according to tests),
• Magnets very well resist against loss of magnetization caused by external fields,
• The use of an elegant layer of noble metals (nickel, gold, silver) causes the element to look better,
• Magnetic induction on the working layer of the magnet turns out to be extremely intense,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, allowing for operation at temperatures reaching 230°C and above...
• Thanks to versatility in shaping and the capacity to adapt to specific needs,
• Huge importance in innovative solutions – they serve a role in HDD drives, brushless drives, medical devices, as well as technologically advanced constructions.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

Drawbacks and weaknesses of neodymium magnets: application proposals

• To avoid cracks upon strong impacts, we recommend using special steel holders. Such a solution secures the magnet and simultaneously improves its durability.
• Neodymium magnets lose their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• They rust in a humid environment - during use outdoors we advise using waterproof magnets e.g. in rubber, plastic
• Due to limitations in creating threads and complex forms in magnets, we propose using casing - magnetic mechanism.
• Health risk resulting from small fragments of magnets pose a threat, if swallowed, which is particularly important in the aspect of protecting the youngest. Furthermore, tiny parts of these devices can complicate diagnosis medical after entering the body.
• With mass production the cost of neodymium magnets is economically unviable,

Detachment force of the magnet in optimal conditions – what it depends on?

Holding force of 3.32 kg is a result of laboratory testing performed under specific, ideal conditions:

• with the application of a sheet made of special test steel, guaranteeing full magnetic saturation
• possessing a thickness of min. 10 mm to ensure full flux closure
• with an ground touching surface
• 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

Magnet lifting force in use – key factors

In practice, the actual holding force is determined by many variables, ranked from most significant:

• Clearance – existence of foreign body (paint, dirt, air) interrupts the magnetic circuit, which lowers capacity rapidly (even by 50% at 0.5 mm).
• Force direction – declared lifting capacity refers to pulling vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of maximum force).
• Base massiveness – insufficiently thick sheet causes magnetic saturation, causing part of the flux to be lost into the air.
• Plate material – mild steel attracts best. Alloy steels reduce magnetic properties and lifting capacity.
• Surface quality – the smoother and more polished the surface, the better the adhesion and stronger the hold. Roughness acts like micro-gaps.
• Heat – NdFeB sinters have a negative temperature coefficient. When it is hot they are weaker, and in frost they can be stronger (up to a certain limit).

* Lifting capacity testing was performed on a smooth plate of optimal thickness, under a perpendicular pulling force, however under attempts to slide the magnet the load capacity is reduced by as much as fivefold. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the holding force.