MP 30x6x10 / N38 - ring magnet

Pros and cons of NdFeB magnets.

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

• They virtually do not lose strength, because even after ten years the decline in efficiency is only ~1% (based on calculations),
• They are resistant to demagnetization induced by external field influence,
• Thanks to the elegant finish, the plating of Ni-Cu-Ni, gold, or silver gives an visually attractive appearance,
• Magnetic induction on the working layer of the magnet turns out to be impressive,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Thanks to freedom in designing and the capacity to modify to unusual requirements,
• Key role in modern industrial fields – they are used in mass storage devices, electromotive mechanisms, advanced medical instruments, also multitasking production systems.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously improves its durability.
• When exposed to high temperature, neodymium magnets experience a drop in power. Often, when the temperature exceeds 80°C, their strength decreases (depending on the size and shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding up to 230°C
• Magnets exposed to a humid environment can rust. Therefore during using outdoors, we suggest using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Limited possibility of producing nuts in the magnet and complex shapes - recommended is casing - magnet mounting.
• Possible danger resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the aspect of protecting the youngest. Additionally, small elements 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 magnetic pulling force – what affects it?

Holding force of 3.42 kg is a theoretical maximum value executed under standard conditions:

• with the contact of a yoke made of special test steel, guaranteeing maximum field concentration
• with a cross-section of at least 10 mm
• with a plane free of scratches
• under conditions of gap-free contact (surface-to-surface)
• for force acting at a right angle (pull-off, not shear)
• at room temperature

Determinants of practical lifting force of a magnet

Please note that the working load will differ influenced by elements below, in order of importance:

• Distance – existence of any layer (paint, dirt, gap) interrupts the magnetic circuit, which lowers power steeply (even by 50% at 0.5 mm).
• Load vector – highest force is obtained only during perpendicular pulling. The force required to slide of the magnet along the surface is standardly many times smaller (approx. 1/5 of the lifting capacity).
• Base massiveness – insufficiently thick sheet does not accept the full field, causing part of the power to be lost into the air.
• Metal type – not every steel attracts identically. Alloy additives weaken the interaction with the magnet.
• Surface finish – full contact is obtained only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – high temperature weakens magnetic field. Exceeding the limit temperature can permanently damage the magnet.

* Holding force was measured on a smooth steel plate of 20 mm thickness, when a perpendicular force was applied, whereas under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate reduces the holding force.