SM 32x225 [2xM8] / N52 - magnetic separator

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to their tremendous field intensity, neodymium magnets offer the following advantages:

• They retain their full power for around 10 years – the loss is just ~1% (according to analyses),
• They show exceptional resistance to demagnetization from external magnetic fields,
• Thanks to the glossy finish and nickel coating, they have an visually attractive appearance,
• They possess strong magnetic force measurable at the magnet’s surface,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to build),
• The ability for accurate shaping or customization to custom needs – neodymium magnets can be manufactured in a wide range of shapes and sizes, which amplifies their functionality across industries,
• Key role in advanced technical fields – they serve a purpose in HDDs, electric motors, diagnostic apparatus and technologically developed systems,
• Thanks to their concentrated strength, small magnets offer high magnetic performance, in miniature format,

Disadvantages of NdFeB magnets:

• They are prone to breaking when subjected to a powerful impact. If the magnets are exposed to physical collisions, it is advisable to use in a metal holder. The steel housing, in the form of a holder, protects the magnet from fracture and additionally reinforces its overall durability,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible power drop (influenced by the magnet’s structure). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Magnets exposed to wet conditions can rust. Therefore, for outdoor applications, we suggest waterproof types made of rubber,
• Limited ability to create internal holes in the magnet – the use of a housing is recommended,
• Health risk due to small fragments may arise, if ingested accidentally, which is notable in the context of child safety. Moreover, minuscule fragments from these magnets have the potential to disrupt scanning when ingested,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Highest magnetic holding force – what affects it?

The given holding capacity of the magnet corresponds to the highest holding force, determined in the best circumstances, specifically:

• with the use of low-carbon steel plate acting as a magnetic yoke
• of a thickness of at least 10 mm
• with a polished side
• with zero air gap
• in a perpendicular direction of force
• under standard ambient temperature

Impact of factors on magnetic holding capacity in practice

In practice, the holding capacity of a magnet is affected by the following aspects, from crucial to less important:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) causes a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity was determined with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under attempts to slide the magnet the holding force is lower. Additionally, even a minimal clearance {between} the magnet and the plate decreases the holding force.