MW 15x4 / N38 - cylindrical magnet

Pros and cons of neodymium magnets.

Apart from their superior holding force, neodymium magnets have these key benefits:

• They have stable power, and over more than ten years their attraction force decreases symbolically – ~1% (according to theory),
• They are extremely resistant to demagnetization induced by external field influence,
• A magnet with a metallic gold surface is more attractive,
• The surface of neodymium magnets generates a powerful magnetic field – this is one of their assets,
• Made from properly selected components, these magnets show impressive resistance to high heat, enabling them to function (depending on their form) at temperatures up to 230°C and above...
• Thanks to versatility in forming and the capacity to adapt to client solutions,
• Huge importance in modern technologies – they are commonly used in computer drives, electric motors, medical equipment, and technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, in miniature format,

Characteristics of disadvantages of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a strong case, which not only protects them against impacts but also raises their durability
• Neodymium magnets decrease 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
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited ability of creating nuts in the magnet and complex shapes - recommended is cover - magnet mounting.
• Health risk related to microscopic parts of magnets are risky, when accidentally swallowed, which is particularly important in the aspect of protecting the youngest. Additionally, small elements of these magnets can complicate diagnosis medical when they are in the body.
• Due to expensive raw materials, their price is higher than average,

Maximum lifting capacity of the magnet – what affects it?

Holding force of 3.32 kg is a result of laboratory testing performed under the following configuration:

• using a base made of low-carbon steel, functioning as a ideal flux conductor
• whose thickness is min. 10 mm
• characterized by lack of roughness
• under conditions of gap-free contact (surface-to-surface)
• during pulling in a direction vertical to the mounting surface
• in temp. approx. 20°C

Determinants of practical lifting force of a magnet

Real force is affected by specific conditions, mainly (from most important):

• Clearance – existence of any layer (rust, dirt, gap) acts as an insulator, which reduces capacity steeply (even by 50% at 0.5 mm).
• Direction of force – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the surface is typically several times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the attraction force (the magnet "punches through" it).
• Material composition – different alloys reacts the same. High carbon content worsen the interaction with the magnet.
• Surface quality – the smoother and more polished the surface, the larger the contact zone and higher the lifting capacity. Roughness acts like micro-gaps.
• Temperature – temperature increase causes a temporary drop of induction. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity was assessed by applying a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet’s surface and the plate lowers the load capacity.