SMZR 25x225 / N52 - magnetic separator with handle

Advantages as well as disadvantages of NdFeB magnets.

Besides their durability, neodymium magnets are valued for these benefits:

• They virtually do not lose strength, because even after ten years the performance loss is only ~1% (based on calculations),
• They show high resistance to demagnetization induced by external field influence,
• The use of an elegant coating of noble metals (nickel, gold, silver) causes the element to look better,
• Neodymium magnets deliver maximum magnetic induction on a small area, which allows for strong attraction,
• Due to their durability and thermal resistance, neodymium magnets are capable of operate (depending on the form) even at high temperatures reaching 230°C or more...
• Thanks to versatility in constructing and the capacity to adapt to client solutions,
• Fundamental importance in modern technologies – they serve a role in hard drives, electromotive mechanisms, medical devices, also multitasking production systems.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of neodymium magnets:

• At strong impacts they can crack, therefore we recommend placing them in special holders. A metal housing provides additional protection against damage and increases the magnet's durability.
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we recommend our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore while using outdoors, we advise using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of making nuts in the magnet and complicated forms - recommended is a housing - mounting mechanism.
• Possible danger related to microscopic parts of magnets pose a threat, if swallowed, which becomes key in the context of child safety. Additionally, small components of these magnets can disrupt the diagnostic process medical in case of swallowing.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

Maximum lifting force for a neodymium magnet – what affects it?

The specified lifting capacity concerns the maximum value, measured under ideal test conditions, meaning:

• on a base made of structural steel, optimally conducting the magnetic flux
• with a cross-section minimum 10 mm
• with a plane cleaned and smooth
• with direct contact (without paint)
• under perpendicular force vector (90-degree angle)
• in temp. approx. 20°C

Impact of factors on magnetic holding capacity in practice

Holding efficiency is influenced by working environment parameters, including (from priority):

• Distance – existence of foreign body (paint, tape, gap) interrupts the magnetic circuit, which reduces capacity rapidly (even by 50% at 0.5 mm).
• Angle of force application – highest force is obtained only during perpendicular pulling. The shear force of the magnet along the plate is typically many times smaller (approx. 1/5 of the lifting capacity).
• Plate thickness – insufficiently thick steel causes magnetic saturation, causing part of the flux to be lost to the other side.
• Steel type – mild steel gives the best results. Alloy steels lower magnetic permeability and lifting capacity.
• Base smoothness – the more even the surface, the larger the contact zone and higher the lifting capacity. Unevenness creates an air distance.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently demagnetize the magnet.

* Lifting capacity testing was conducted on a smooth plate of optimal thickness, under a perpendicular pulling force, whereas under shearing force the holding force is lower. Additionally, even a slight gap {between} the magnet and the plate reduces the holding force.