BM 380x180x70 [4x M8] - magnetic beam

Strengths and weaknesses of NdFeB magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They virtually do not lose strength, because even after 10 years the decline in efficiency is only ~1% (in laboratory conditions),
• Neodymium magnets prove to be exceptionally resistant to loss of magnetic properties caused by magnetic disturbances,
• The use of an aesthetic layer of noble metals (nickel, gold, silver) causes the element to have aesthetics,
• Neodymium magnets deliver maximum magnetic induction on a contact point, which increases force concentration,
• Thanks to resistance to high temperature, they are able to function (depending on the form) even at temperatures up to 230°C and higher...
• Thanks to freedom in designing and the ability to adapt to complex applications,
• Significant place in modern technologies – they are utilized in computer drives, electromotive mechanisms, diagnostic systems, as well as multitasking production systems.
• Relatively small size with high pulling force – neodymium magnets offer high power in small dimensions, which allows their use in compact constructions

Cons of neodymium magnets: application proposals

• At strong impacts they can break, therefore we recommend placing them in steel cases. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• Neodymium magnets lose 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 stability even at temperatures up to 230°C
• Magnets exposed to a humid environment can corrode. Therefore when using outdoors, we recommend using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of creating threads in the magnet and complex forms - recommended is a housing - magnetic holder.
• Possible danger resulting from small fragments of magnets pose a threat, when accidentally swallowed, which gains importance in the context of child health protection. Furthermore, tiny parts of these devices can disrupt the diagnostic process medical when they are in the body.
• Due to neodymium price, their price exceeds standard values,

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

Holding force of 0 kg is a theoretical maximum value executed under the following configuration:

• using a sheet made of mild steel, serving as a magnetic yoke
• with a cross-section of at least 10 mm
• characterized by even structure
• under conditions of no distance (metal-to-metal)
• for force applied at a right angle (in the magnet axis)
• in temp. approx. 20°C

Key elements affecting lifting force

Effective lifting capacity impacted by working environment parameters, including (from most important):

• Space between magnet and steel – every millimeter of distance (caused e.g. by varnish or dirt) diminishes the pulling force, 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 standardly several times lower (approx. 1/5 of the lifting capacity).
• Base massiveness – insufficiently thick sheet does not close the flux, causing part of the flux to be lost into the air.
• Material type – ideal substrate is high-permeability steel. Stainless steels may generate lower lifting capacity.
• Surface quality – the smoother and more polished the surface, the better the adhesion and stronger the hold. Unevenness creates an air distance.
• Temperature influence – high temperature weakens pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity was assessed using a polished steel plate of optimal thickness (min. 20 mm), under perpendicular detachment force, however under attempts to slide the magnet the load capacity is reduced by as much as 75%. In addition, even a slight gap {between} the magnet and the plate decreases the load capacity.