SM 18x275 [2xM5] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their strong magnetism, neodymium magnets have these key benefits:

• Their magnetic field is durable, and after around 10 years, it drops only by ~1% (according to research),
• Their ability to resist magnetic interference from external fields is notable,
• Because of the brilliant layer of gold, the component looks aesthetically refined,
• The outer field strength of the magnet shows remarkable magnetic properties,
• These magnets tolerate high temperatures, often exceeding 230°C, when properly designed (in relation to profile),
• With the option for tailored forming and precise design, these magnets can be produced in numerous shapes and sizes, greatly improving application potential,
• Important function in new technology industries – they find application in computer drives, electric drives, healthcare devices or even technologically developed systems,
• Compactness – despite their small size, they deliver powerful magnetism, making them ideal for precision applications

Disadvantages of neodymium magnets:

• They are prone to breaking when subjected to a heavy impact. If the magnets are exposed to shocks, it is advisable to use in a protective case. The steel housing, in the form of a holder, protects the magnet from fracture and additionally increases its overall durability,
• Magnets lose power when exposed to temperatures exceeding 80°C. In most cases, this leads to irreversible magnetic decay (influenced by the magnet’s dimensions). To address this, we provide [AH] models with superior thermal resistance, able to operate even at 230°C or more,
• Due to corrosion risk in humid conditions, it is common to use sealed magnets made of protective material for outdoor use,
• Limited ability to create precision features in the magnet – the use of a mechanical support is recommended,
• Safety concern related to magnet particles may arise, especially if swallowed, which is significant in the context of child safety. It should also be noted that miniature parts from these devices may complicate medical imaging when ingested,
• Higher purchase price is one of the drawbacks compared to ceramic magnets, especially in budget-sensitive applications

Best holding force of the magnet in ideal parameters – what contributes to it?

The given strength of the magnet corresponds to the optimal strength, assessed in ideal conditions, namely:

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

Determinants of practical lifting force of a magnet

The lifting capacity of a magnet depends on in practice key elements, from primary to secondary:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause 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 using a steel plate with a smooth surface of suitable thickness (min. 20 mm), under perpendicular detachment force, however under shearing force the lifting capacity is smaller. Additionally, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.