SMZR 32x125 / N52 - magnetic separator with handle

Advantages as well as disadvantages of neodymium magnets.

Besides their high retention, neodymium magnets are valued for these benefits:

• Their power remains stable, and after around ten years it decreases only by ~1% (theoretically),
• Neodymium magnets are characterized by remarkably resistant to loss of magnetic properties caused by external interference,
• The use of an metallic finish of noble metals (nickel, gold, silver) causes the element to look better,
• The surface of neodymium magnets generates a maximum magnetic field – this is a distinguishing feature,
• Neodymium magnets are characterized by extremely high magnetic induction on the magnet surface and are able to act (depending on the shape) even at a temperature of 230°C or more...
• In view of the option of precise molding and adaptation to custom projects, NdFeB magnets can be created in a broad palette of shapes and sizes, which expands the range of possible applications,
• Fundamental importance in future technologies – they are commonly used in HDD drives, electric drive systems, advanced medical instruments, as well as other advanced devices.
• Thanks to efficiency per cm³, small magnets offer high operating force, with minimal size,

What to avoid - cons of neodymium magnets and proposals for their use:

• At strong impacts they can break, therefore we advise placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's durability.
• When exposed to high temperature, neodymium magnets suffer 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
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Due to limitations in creating threads and complicated forms in magnets, we propose using casing - magnetic mechanism.
• Potential hazard resulting from small fragments of magnets pose a threat, in case of ingestion, which is particularly important in the context of child safety. Additionally, small components of these magnets can be problematic in diagnostics medical after entering the body.
• Higher cost of purchase is a significant factor to consider compared to ceramic magnets, especially in budget applications

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

Breakaway force was defined for optimal configuration, assuming:

• with the contact of a sheet made of special test steel, ensuring maximum field concentration
• possessing a thickness of min. 10 mm to avoid saturation
• with an polished touching surface
• without any insulating layer between the magnet and steel
• during pulling in a direction vertical to the mounting surface
• in neutral thermal conditions

Impact of factors on magnetic holding capacity in practice

Real force is affected by working environment parameters, mainly (from priority):

• Gap (betwixt the magnet and the plate), because even a microscopic distance (e.g. 0.5 mm) can cause a reduction in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Load vector – maximum parameter is obtained only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is standardly several times smaller (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be sufficiently thick. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Steel grade – the best choice is high-permeability steel. Cast iron may attract less.
• Surface finish – full contact is obtained only on smooth steel. Any scratches and bumps create air cushions, weakening the magnet.
• Thermal environment – temperature increase causes a temporary drop of force. Check the maximum operating temperature for a given model.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under perpendicular forces, whereas under attempts to slide the magnet the load capacity is reduced by as much as 5 times. In addition, even a small distance {between} the magnet and the plate reduces the lifting capacity.