BM 450x180x70 [4x M8] - magnetic beam

Pros and cons of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• They have constant strength, and over more than ten years their performance decreases symbolically – ~1% (in testing),
• They are noted for resistance to demagnetization induced by external magnetic fields,
• Thanks to the reflective finish, the coating of nickel, gold, or silver gives an clean appearance,
• Neodymium magnets generate maximum magnetic induction on a contact point, which allows for strong attraction,
• 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 ability to modify to specific needs,
• Fundamental importance in future technologies – they find application in HDD drives, electric motors, diagnostic systems, as well as modern systems.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets and ways of using them

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• Neodymium magnets decrease their force under the influence of heating. As soon as 80°C is exceeded, many of them start losing their force. 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
• Limited ability of making threads in the magnet and complex shapes - preferred is cover - magnet mounting.
• Possible danger to health – tiny shards of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child safety. Furthermore, small components of these magnets are able to complicate diagnosis medical in case of swallowing.
• Due to expensive raw materials, their price is relatively high,

Maximum holding power of the magnet – what it depends on?

Magnet power was defined for ideal contact conditions, taking into account:

• using a base made of high-permeability steel, serving as a ideal flux conductor
• possessing a massiveness of at least 10 mm to avoid saturation
• characterized by even structure
• with zero gap (without paint)
• under axial force direction (90-degree angle)
• at standard ambient temperature

Key elements affecting lifting force

Real force is influenced by specific conditions, including (from most important):

• Gap between surfaces – even a fraction of a millimeter of distance (caused e.g. by veneer or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Load vector – highest force is obtained only during pulling at a 90° angle. The shear force of the magnet along the surface is typically many times lower (approx. 1/5 of the lifting capacity).
• Element thickness – for full efficiency, the steel must be sufficiently thick. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Chemical composition of the base – mild steel attracts best. Higher carbon content lower magnetic permeability and lifting capacity.
• Surface finish – full contact is possible only on smooth steel. Any scratches and bumps reduce the real contact area, reducing force.
• Temperature – temperature increase causes a temporary drop of force. It is worth remembering the maximum operating temperature for a given model.

* Lifting capacity testing was performed on plates with a smooth surface of suitable thickness, under perpendicular forces, whereas under shearing force the lifting capacity is smaller. Additionally, even a slight gap {between} the magnet’s surface and the plate reduces the load capacity.